Tiny Savonlinna Airport (IATA: SVL) is served by Flybe , which offers flights from Helsinki to Savonlinna up to two times per week day. Advance fares start from €32/one way, cheaper than the train, but go up quickly as the plane fills. There is a shuttle service to and from the bus station, which departs one hour before the flight leaves.
Savonlinna is stretched out on a series of islands in the middle of Lake Saimaa. While you can cover the central parts on foot, you'll need to resort to buses (or rent a car) to access the suburbs. If you want to rent a car, there is a Hertz rental office at the waterfront, near Hotel Tott. Savonlinna is surrounded by lakes and you can also go around town centre by a cruise ship. If you have someplace specific in mind to spend the day, it is probably cheaper to get a taxi, however. Taxi's are plentiful, and certainly cheaper than renting a car for the day, if you are only going to one or two places.
Medieval Olavinlinna (St. Olaf's Castle)  is the city's symbol and main attraction. Built in 1475 by Danish knight Erik Axelsson to protect the eastern border of the Swedish-Danish Kalmar Union, it was named after the patron saint of knights, St. Olaf. The Russians were soon on the offensive, but the castle withstood several sieges before capitulating in 1714. The Swedes recaptured it in 1721, but lost it again in 1743, and it stayed in Russian hands ever since. This also explains why it has stayed in such good shape: for the Russians, it was far inland and militarily useless, and hence not a target for the enemy either.
Today, Olavinlinna is the world's northernmost medieval fortress and easily Finland's best-preserved and most attractive, and it's quite a sight perched on the shores of the lake. The interior, though, is surprisingly small and sparse (virtually all furniture and decorations were lost in fires in around 1870). Guided tours take one hour. There are two small museums inside the castle:
Castle Museum, covers the castle's history
Orthodox Museum, with Russian Orthodox icons and paraphernalia
The castle is open daily 10AM-6PM in summer, 11AM-4PM the rest of the year. Guided tours in English run every hour in summer (enquire in advance at firstname.lastname@example.org in other seasons), but you can still visit the museums and courtyards without it.
There are plenty of sightseeing cruises around Lake Saimaa. If you're extremely lucky, you just might spot the very rare Saimaa Ringed Seal (saimaannorppa).
Read more about the cruises from the web pages of Savonlinna Travel 
Savonlinna Provincial Museum is located on the island of Riihisaari. From the same building you can find also the Nestori - Saimaa Nature Exhibition centre run by Metsähallitus which also provides hiking information. The Provincial Museum concentrates on the history of South Savo and particularly on preserving, studying and presenting the history of sailing on Lake Saimaa. During the summer you may visit also the unique steamships behind the museum.
Art Centre Retretti in Punkaharju, 30 km from Savonlinna, is one of the biggest art centre in Nordic Counties and build partly under the caves. Changing exhibitions every summer.
Lusto - Finnish Forest Museum also in Punkaharju, is a national museum specializing in forests and forestry, and a versatile exhibition and culture centre. Lusto is open all year round and it attracts approximately 30 000 visitors every year. The museum was opened to the public in 1994 and it is one of the largest specialized museums in Finland.
World`s biggest wooden church in Kerimäki is an attraction worth to visit, location 24 km from Savonlinna.
The city is renowned for its yearly Opera Festival, organized within St. Olaf's Castle. There is also a Ballet Festival at the same place earlier in the year.
Visit Spahotel Casino. It is situated on an island in the city centre. It offers swimming pools, massaging showers, a jacuzzi, a children's pool, Finnish saunas and Turkish saunas (steam rooms) also for day visitors.
Sulosaari. A small island on the other side of the Spahotel Casino, as seen from the city centre. A very picturesque, and quiet place for a stroll. In wintertime, you can include it in a lake-traversing trek, provided the ice is thick enough to walk on (which it usually is).edit
Linnansaari National Park. Linnansaari National Park in the middle of Lake Haukivesi, a part of Lake Saimaa, represents Finnish lakeland at its best. With its hundreds of islands and broad open waters it is a paradise for boaters and nature lovers. The National Park offers possibilities for day trips, as well as for several days camping and boating/canoeing holidays. It provides also possibilities for lot's of activities like fishing, canoeing, hiking, Saimaa Ringed Seal watching safaris and skating during the winter season.edit
M/S Puijo, ☎ +35815250250, . The century old ship M/S Puijo offers cruises along the Heinävesi route (Savonlinna-Kuopio) from mid-June to mid-August. One can hop on the ship from a number of piers between the two cities. Outside of the regular schedule it is possible to organize your own cruise. The Heinävesi route is said to be one of the worlds most beautiful inland waterways.edit
During the morning and afternoon, the best place to eat is the market square by the lake, where you can get Eastern Finnish delicacies like lörtsy meat pies and freshly fried muikku (vendace, a type of freshwater herring).
Roof Terrace of Savonlinnan Seurahuone,  Try the famous local delicacy called Muikku - a small white fish (Vendace)
Liekkilohi, next to market, tel. 050 3105 850, . The flagship floating restaurant of a franchised chain, the menu here is simple: pick either one of their trademark flame-broiled salmon, fried muikku, the un-Finnishly immodestly named "world's best fish soup" (not quite, alas) for around €15, or go whole hog and get them all plus the amazing cold fish buffet with 17 types to sample for €35. Prices may be negotiable if it's quiet and you're in a group.
Best Western Spahotel Casino, . Offers rooms in beautiful surroundings, on an island in the town centre.
Perhehotelli Hospitz, . Next to the Olavinlinna Castle.
Original Sokos Hotel Savonlinnan Seurahuone, . The traditional wing of Hotel Seurahuone was built in 1956, and it was renovated in 1989 when the new wing was completed. The hotel has 80 rooms - most of them with a view over the lake.
Pietari Kylliäinen, . City hotel located close to both services and nature.
Lomamokkila,  cosy farm holiday place 12 km from Savonlinna, near the airport. Highlander cattle, cats and dog are welcoming you to spend your holiday.
Hotel Herttua,  25 km from Savonlinna, in Kerimäki, on crystal clear Lake Puruvesi.
Kerimaa Holiday Resort,  15 km from Savonlinna, in Kerimäki, next to 18 hole golf course.
Holiday Resort Järvisydän, . 40 min. drive from Savonlinna, in the village of Rantasalmi, right next to Linnansaari National Park, offering excellent surroundings for nature activities all year around. Summer cottages and villas. Medieval style restaurant Piikatyttö and the wine cellar.
SaimaaHoliday Oravi [http://www.saimaaholiday.fi/oravi) 45 km from Savonlinna, next to Linnansaari National Park. Safari house, for rental equipment and guided nature activities and safaris.
Kuus-Hukkala holiday village and camping 40 km from Savonlinna, towards Juva and Mikkeli. Lada Niva safaris and a winter driving school!
Punkaharju Resort 30 km from Savonlinna, in beautiful Punkaharju. Cottages, new restaurant Paviljonki and Kesämaa water and amusement park for children.
Kruunupuisto 35 km from Savonlinna, in the middle of Punkaharju ridge area.
Hotel Rantakatti 35 km from Savonlinna, in the middle of Punkaharju ridge area.
Ruoke Holiday Resort 60 km from Savonlinna, on Lake Puruvesi and near of village Kesälahti. Nice fishing possibilities.
Kerimäki — featuring the world's biggest wooden church
Punkaharju — visit the beautiful ridge area only 30 min from Savonlinna
Rantasalmi — featuring Linnansaari National Park, 50 km from Savonlinna
This is a usable article. It has information for getting in as well as some complete entries for restaurants and hotels. An adventurous person could use this article, but please plunge forward and help it grow!