Myself and my girlfriend recently travelled from Chiang Rai to Luang Prabang and there seems to be alot of confusion as to the process so I thought id give an up to date review.
We got the green bus from the bus terminal 1 in Chiang Rai to Chiang Khong, bus leaves every hour from 6am - 5pm. I think it was bus number 4 you just get on and pay once your on your way, takes about 2.5 hours 65 baht. I believe you used to get the bus to Chiang Khong then get the boat over the river then it changed to bus to Chiang Khong then long tuk tuk to the new friendship bridge. Now they actually have tuk tuks waiting by the turning to the new friendship bridge so not going back on yourself. I think it was 80 Baht for the both of us?
Once at the new friendship bridge its very simple to find which way to go we got there early as we wanted to get the boat the same day and only a few of us there. They check your passport, stamp your exit visa then you go through and buy a bus ticket for 20 baht to take you over the new friendship bridge. Buses are every 20-30 mins I believe. If you dont have dollars or a passport photo don't worry you can get dollars both sides and photo Laos side.
Now your over the bridge which is literally a few mins you go through immigration fill out the forms passport control etc. Our visas were $35 dollars each (UK citizen) if you don't have the exact amount don't worry you'll get change in either kip or baht. i didn't have a passport photo so had to pay 40 baht assuming they'd take my picture but nope! just no picture.. once your through get some kip is the best but baht is taken and dollars but best rate using kip as we found out when we paid for the slow boat with dollars! We paid 50,000 KIP for the tuk tuk to the slow boats you dont really have much option as they are the only ones there if you dont pay you'll have about a 10km walk!
We got to the slow boat pier after the ride on the dodgiest tuk tuk we've been on so far! Go to the ticket office and get a ticket from this miserable woman its 220,000 kip each for the slow boat to Luang Prabang. As we did'nt have any kip as did'nt have time to find a cashpoint we paid $35 each!! The boat leaves at 11am each day so best to get the early as pos as not to sit at the back, the engine is SO loud as we found out! They recommend a guesthouse and I know alot of people say dont go with the one they say but for 90,000 kip double room we thought it was reasonable and saves the hassle trying to find somewhere when we're there. We ended up leaving about 11.30 as they obviously wanted to fill the boat. The journey isnt so bad nice view but it is about 7 hours! Seats are out of old cars so recline a little. They make a few stops along the way to drop off/pick up supplies/people in the small villages.
We arrived in Pakbeng and being monsoon it was raining like crazy! There are a handful of guesthouse owners waiting seeing if you want a room luckily we already had one so didnt have to trek around in the rain, just a quick run up the road. Room was clean and comfortable which is all you need for a quick stop. We chucked our bags down and went for dinner at this indian was so nice! Best indian ive had in a long time and very cheap.
In the morning get on the boat early again about 8- 8.30 for the better seats and get some supplies beforehand. It is a different boat for the second leg of the journey just ask at the pier which one for Luang Prabang, ended up leaving about 9.30. Journey once again was about 7 hours so another dead bum! When you arrive in Luang Prabang does'nt really seem like you'd expect as you get dropped off on the outskirts and people were unsure if this was it or not, it actually is. Grab your bags and go up the hill where there is a little office selling tuk tuk tickets, buy a ticket for 20,000 kip each fixed price to take you to your hotel/hostel/guesthouse in town. Thats it! Simple as that! Hope this clears things up for people who were unsure as we were being the new bridge etc.