The two day boat trip from the Thai border to Luang Prabang gets very mixed reviews from everyone we met who did it so we were a little apprehensive about doing it. It is possible to do the trip in seven hours on a speedboat, but after reading that the Lonely Planet calls them "death traps" and seeing them first hand bouncing across the water we decided very quickly against that option. In the end though the boat trip turned out to be really quite good...