Chiang Khong is the Thai counterpart to the Lao border town of Huay Xai, just across the Mekong. Chiang Khong is a small, sleepy town with one main road and no night life. It has a Friday market, a lot of temples, a craft village with a busy market and a temple. The best time to visit is from October to January, or on the April 18 Giant Catfish Festival when baby giant catfish are taken to the Mekong river.
From Huay Xai in Laos by a short ferry trip (10,000 Kip) across the Mekong (6am to 6pm). Thai Immigration here seems to lack both computers and the annoying cameras now installed in Bangkok's airport and, consequently, is extremely quick. However, arriving by this overland route means that you will only be given a tourist visa valid for fourteen days, compared with the 30 days you would get flying into Bangkok. The ferry is at the northern end of Chiang Khong: if you want to move on without stopping in the city, take a tuktuk to the bus station in town for 30 baht per person, or you can walk 3km.
From Chiang Rai local buses go regularly (mostly every half hour) from 5.00 AM to 16.00 PM. It should take about 2h but the driver take it slow and it could happen on the way he will stop to buy the dinner, so probabilly 2.30h or more
From Chiang Mai by minibus for 250 baht or by "green bus" (making many stops) for about 200 baht, by public bus is 150-270 bath.
anyway the most advised way is to go by bus to Chiang Rai for 94-263 baht (3h) and then take a bus to Chiang Khong.
by bus from other major cities in Northern Thailand and Isaan. Daytime and overnight buses run directly from Bangkok's Northern Bus Terminal (Moh Chit) to Chiang Khong every day. There are also 5 overnight buses from Moh Chit which leave at 19.00 pm and arrive at Chiang Khong the next morning at 8.00 am, and one daytime bus which leaves Moh Chit at 7.00 am and arrives in Chiang Khong at 20.00 pm.
The riverfront area can be seen on foot but it's worth getting a tuk-tuk or taxi for the trip out to the bus station. Small ferries cross the river every few minutes for about 40 baht (10,000 kip). The border crossing closes at 18:00.
If you want to look around Chiang Khong the best way is rent a bike or motorbike to visit local villages and the banks of the Mekong.
H'mong Village (10 km.)
Nam Chang Dam for fishing and swimming (7 Km.)
Thai Lue village with cloth weaving(15 Km.)
Waterfall (near to H'mong village)
Thai sauna at Baanrimtaling
The Chiang Khong Fishery Station is able to inseminate and breed this largest fresh-water fish. Fingerlings bred here have been released in several rivers.
Learn Thai cooking at Baanrimtaling
Visit the golden triangle by motorbike - 1 day trip(60 Km.)
Visit a rustic village near the Mekong Village.
The Hub -Bike Museum ran by an Professional cyclist Alan bate that has a great selection of bikes 
Temples in Chiang Khong:
Wat Sri don Chai
Wat Sob som
Wat Hat Krai
Wat Hou weing
Wat Tung Duk
There are several ATMs in the town - Kasikorn Bank, GSB, Siam Commercial Bank, Krung Thai Bank and a new machine in front of the 7/11 at the bus station. All banks are closed on Saturday and Sunday but you should be able to use the ATMs. If you are heading to Laos get your money here because in houay xai the maximum withdrawal per transaction is 700,000kip and exchange rates from baht to kip are quite ok.
Laos currency (kip) can only be officially exchanged inside Laos. Thai banks will not exchange Laos currency. Chiang Khong ATM will not disburse kip. Chiang Khong moneychangers will exchange for a fee. The Laos bank in Huay Xai and the ATM there will disburse kip. Thai baht and US dollars are readily accepted in Laos. At good rates.
Laos visas are more economical if bought with US dollars instead of baht.
Rimnam Guesthouse and Restaurant 166/1 moo 12. River view.
BaanRimtaling Home stay & Restaurant have a Vegetarian food and good Thai curry, call 084-6155490 Learning Thai cooking How to make Curry, Pad Thai, Tomyam. After cooking you have your own dinner.
Visit a small market at Baan Hat Krai village to see catfish for sale and some produce from the jungle, for example mushrooms and river weeds from the Mekong.
Restaurant above Boom Guesthouse on the other side of the street - Is run for 25 years by a very nice lady who does even some talking with the falangs. And good food too!
Nang Nuan (นางนวล) Ban Hat Khrai, Tel: 0 5379 1271 (Thai food)
Bamboo Mexican - great food done right, really friendly owners. Half way down main street on river side of the road.
There are very few bars in Chiang Khong, e.g. Alan's 'Hub' .
Baan Pak Pon, also known as PP Home, offers large, very clean rooms with fan or air con for 350 - 600 Baht. All rooms have hot water and wifi and include a nice veranda to sit outside the rooms in private. The verandas offer a scenic view over the Mekong River to Laos and Huayxai. Family owned by very friendly people. Defenitely one of the cleanest guesthouses in Chiang Khong. Email: email@example.com.
Ban Fai Guesthouse (บ้านฝ้าย เกสต์เฮาส์) 108 Mu 8 Ban Wiang Kaew, Tambon Wiang (Tel: 0 5379 1394), 9 rooms: 80-150 baht
Ban Rim Khong (บ้านริมโขง) 278/3 Mu 7 Ban Had Krai, Tambon Wiang (Tel: 0 8 1281 9966, Tel & Fax:0 5379 1269), 4 rooms: 200-400 baht
BaanRimtaling (บ้านริมตลิ่ง) 99/4 Mu 3 Ban Sopsom Tambon Wiang -- Tel# 0846155490 (Thailand) (66) 846155490 (International), English spoken. Ask for Maleewan. Guesthouse website (www.chiang-khong-guesthouse.com ) , Rooms: 100-450 baht. Dorms, Single and Double Rooms, and Bungalows, all with hot shower. Guesthouse overlooks Mekong River. 400m from bus stop/7-Eleven towards Wat Sob Som. Directions on green sign at 7/11. Free pickup at bus stop. Free ride to border in morning. Free internet and wifi.
Ban Tammila (บ้านตำมิละ) 113 Mu 8 Tambon Wiang (Tel & Fax: 0 5379 1234), 9 rooms: 200-500 baht
Boom Guesthouse Rooms from 250 baht. But nice style. Everything in wood, including the terrace with view over the Mekong.
Chom Khong Guesthouse tel. +66-53655661
Chiang Khong River View Hotel 141 Moo 12; tel. +66-53791375 Hot showers, river views, some rooms with air-con. 350-600 baht.
Nam Khong Gueshouse 408 Moo 1; tel. +66-53655102
Rimnam Guesthouse and Restaurant 166/1 moo 12 350-500 baht.
Chiangkhong Green Inn. 89/4 Moo 2 T.Wiang Chiangkhong; tel. +66-53-791009 (GreenInn_CK@hotmail.com) Dorms, single, double, triple rooms. 200-1000 baht.
It seems very popular for guides on the pre booked slow boat trip to try encourage people to switch to the bus to Luang Prabang for the same price. They tell horror stories of floods, mosquito hordes, unexpected third nights spent on the slow boat and crooks in Pak Beng. Presumably this is designed so they can pocket the difference between the cheaper bus ticket and the slow boat you already paid for when you pre booked. On our trip (July 2011) around 80% of the group decided to take the bus instead. Many other groups on the slow boat commented that this was also the case in their groups. Don't Fall for it!!
To get an impession of the slowboat trip, watch a movie here: 
Laos - most guesthouses can arrange a package deal with food and overnight accommodation in Pakbeng for the trip to Luang Prabang, but it is fairly simple to do as an independent traveller as well. It's worth crossing the border a day early and spending the night in Huay Xai to be up and ready to catch a boat down the river first thing in the morning.
Edit - The Slow Boat (now only one) is advertised to leave at 10:30AM. But, always leaves around 11:00AM to 11:30AM. A good time to cross the border to go on the slow boat is 9:00AM. The Thai Immigration office can be quite congested at the 8:00AM opening.
Getting to the slow boat requires an exit stamp from Thailand Immigration(about 5 minutes), crossing the river (about 5 minutes), getting a Laos visa (about 20 minutes), and go upriver about 1km. Walk or tuk-tuk.
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!