Catalonia has a great variety of different landscapes very close to each other, mountains on the Pyrenees (at the border with France), green hills on north of the country, agricultural planes on the west and beaches on the east.
What to visit;
Catalonia is today an autonomous region within Spain, but in fact has an older history as an independent territory of the Crown of Aragon which in some ways historically predates Spain itself. The region gained its current autonomous status first in the Republican era (1930s) and then again after Franco's death in 1975 and continues to press for more political and economic autonomy, mainly in the form of the right to collect and spend larger and larger portions of tax money locally. This has been the source of some conflict with other regions of Spain that don't have these expectations. Steer clear from political debates, as these usually don't lead anywhere.
Catalan (Català), spoken in Catalonia, Balearic Islands, most of Valencia region, a strip in Aragon, Andorra, Alguer-Alghero (little city of Sardinia - Italy) and, Roussillon (an area in the south of France sometimes called Catalunya Nord that corresponds roughly with the department of Pyrénées-Orientales). It is a Romance language. You will be very welcome if you try to say some words in Catalan while you are in Catalonia, and phrases such as "Bon Dia" and "Adéu" are heard even when people then go on to speak Castillian.
Visitors who speak Spanish should note that it is called "Castellano" (Catalan Castellà), and that while most people in Catalonia are bilingual in Catalan and Spanish, some people may be reluctant to answer in Spanish, especially away from Barcelona and areas frequented by many tourists. This is due the historic fact that during the Francisco Franco dictatorship the Spanish language was for a time imposed on Catalonia by law and the native Catalan language prohibited. Normally, answering in Catalan to a question asked in Spanish is the polite way to inform the asker that conversation can continue in Catalan if it is desired. If you get an answer in Catalan, just say politely that you do not understand, and you will be without problem in most cases.
Barcelona's airport, called el Prat, is about 10 km to the city centre. Once there, you can go to the centre by train (every 30 minutes, stopping at Sants and Plaça de Catalunya), by bus (Aerobus), that stops in the same places and with the same frequencies. The bus is the more expensive option, with the added possibility of traffic jams. Both services finish at 23:00.
Two local buses, EA (during the day) and EN (at night) also serve the airport, however these are not particularly frequent and only run as far as the Plaça d'Espanya, which is not particularly central. However, for those on a shoestring budget they may be a good option as they are fairly cheap.
There is quite a good taxi service, the only way to reach the centre directly if you arrive by night. The fares are about €12 if you go to the centre, but this can change depending of the time of the day and, of course, the part of the city you want to reach. All Barcelona taxis are painted black and yellow and are easily recognisable.
Of course, you can rent cars and there is a big car park, though it is quite expensive if you leave your car there for more than a couple of hours.
el Prat airport is served by a number of airlines, including EasyJet, BMI, Virgin Air, Volare, MyTraveLite...
Other airports in Catalonia are:
The main train station in Barcelona is called Estació de Sants, but the most central ones are Plaça de Catalunya (most local and regional trains) and Passeig de Gràcia (serving some local and most long-distance lines).
The Spanish train company is called RENFE . Barcelona is very well connected by train with Madrid, Valencia (City), Zaragoza and the Basque Country in particular and with the whole country in general.
There's also a Catalan train company Ferrocarrils de la Generalitat de Catalunya  (FGC), which serves destinations near Barcelona, and some tourist routes. It also operates a funicular service in the Pyrenees.
Buses and coaches connect the principal cities to many national and international locations, and it's the only public transport to get to many local places in Catalonia.
The most important bus stations are: Estació de Sants (Barcelona), mainly for international routes, is next to the train station and very well connected. 'The Estació del Nord (also in Barcelona), close to Passeig de Sant Joan, is the main bus station for medium and long routes - the nearest metro (Line 1) and RENFE station is Arc de Triomf.
The routes inside Catalonia are held by different companies, which leave from different places. Every town has normally only one company, so you should ask at some information point, or check online  which, although in Catalan, is quite easy to use (put the origin at the left, the destination at the right, and gives the name of the company and it's telephone number).
Catalan "Festes" or Festivals
Catalonia has hundreds of "festes" that go on around the region every week of the year. The closest word in English to translate "Festa" would be "Festival" but this is inadequate to describe the type of celebration that exists in Catalonia. "Festes" are ritual like celebrations that have been passed down through generations of people for more than 700 years. They are organized by the people of a town for their own enjoyment, and not for any commercial interest. "Festival" (which also exists in the Catalan and Castilian languages) denotes an event that is usually organized by a specific group of people for a particular market, and is often motivated by economic interest.
“Festes” have ritual like sequences of events that usually involve Giants, Devils, Human Castles and processions. A magical atmosphere is created at the “festa”, almost like a type of Catharsis. “Festes” stem from Medieval Times when fantastical dragons and Giants were created to instruct people about religion in church services. Shortly after the fantastical creatures became a part of the Corpus Christi processions that paraded through the town during the summer. The importance given to these folkloric elements has gradually increased over time and now they have assumed a national importance. Nowadays, these traditions are associated with Catalan identity as something that is individual and separate from the rest of Spain.
These “festes” are not greatly publicized by the Catalan government for foreign people. A new company that takes people on cultural tours of these festes has recently begun. culTOURa aims to show foreign visitors to Catalonia these special and defining traditions, without spoiling the festes and turning them into a commercial event. culTOURa offers people the possibility to enjoy and participate in the best stunning Catalan festivals and traditions 
Because of its geographical location and terrific range of habitats, including dryland steppes, rocky coastlines, mountains and some of the most important wetland sites in Europe, Catalonia has a greater variety of bird life than anywhere else on the peninsular, with 95% of Iberia's and 50% of the whole Palearctic's recorded bird species.
Some of the most sought-after are Lammergeier, Black Woodpecker, Wallcreeper, Bonelli's Eagle, Lesser Grey Shrike, Dupont's Lark (recognised as probably extinct in Catalonia in 2006), Little Bustard, Pin-tailed Sandgrouse, Audouin's Gull and Lesser Crested tern. The most important sites are Cap de Creus, Aiguamolls de L'Empordà, Barcelona's Llobregat Delta, the Parc de Garraf, Ebro Delta, Steppes of Lleida and, of course, The Pyrenees.
There are a few companies that will organise tours for you, or even offer free advice, including Catalan Bird Tours and Oliva Rama Tours. There is also the Birdinginspain.com web site which offers birding sites and itineraries and lots of other useful information to help the visiting birder plan his or her trip to Catalonia.
There are lots of good places to eat. At lunch time (13-15:00 approx.), a lot of Restaurants and Bars offer Menú del dia (Menu of the day - Prix Fixe), usually consisting of a choice of four starters, four main courses, wine and bread for at a reasonable price. Some bars also offer "Plats Combinats" which are a few items served together at reasonable prices - eg Hamburger, egg and chips. At dinner time (20-23:00 approx), a Menú is not so frequent.
In all the medium sized cities, you can expect to find a large range of possibilities.
Usually announced as Cuina Casolana, based on the purposes of the Mediterranian diet: Soups, salads, meats, fish and seafood, snails (especially in Lleida during "L'Aplec del Cargol" by early May), desserts ("Crema catalana" or catalan cream, "Braç de gitano" which is a long roll made of whipped cream and sponge cake) pastries...
Books to read
Consider checking books by Carmen Casas, a restaurant critic and a world-renowned expert on Catalan cuisine.
Cuisines from other regions can be readily found in cities of Catalonya:
Don't miss the good Catalan wines and Caves. Catalonia has had a very rich tradition of wine makers through history, and nowadays is a credited producer of world famous wines. "Penedès", "Priorat", "Costers del Segre", "Alella" and "Terra Alta" are good "D.O."s ("Denominació d'Origen" or designation of origin, the spanish administrative division to control and preserve wine producing areas). Sangría is also served in most restaurants, with large variations in quality.
Catalonia is usually a safe place. Be aware of pickpockets in crowds, and don't leave your car in the rest areas in motorways. Tourist areas such as Las Ramblas in Barcelona city attract many petty thieves, and you should be vigilant around these areas. As a tourist, you are a target for thieves. They can spot you and you cannot spot them. Do not carry all your money and documentation in the same bag or pocket. If you have been robbed, always go to the police.
If you travel try to follow traffic regulations or you may be fined. Notice that you will have to pay in cash immediately otherwise your car will be removed from the road. Therefore have at least 150 EUR with you for that occasion.
It is advisable not to wear any Spanish symbols. Spain national football (soccer) tops, Spanish flags or Real Madrid and Atletico Madrid club paraphernalia are best avoided. Alhough no assaults on people wearing them have been recorded, some people might be upset about them.
Take into account that Catalans are divided amongst those who support independence and others who support union with Spain. If speaking to strangers, avoid political topics as it can cause upset or offend.