This bit of the trip is causing me some concern. I would really like to take the boat from Luang Prabang to Nong Khiaw and then overland to Luang Namtha and onwards to Houayxai. Unfortiunately I am just not going to have the time to do this unless I find Vang Vieng to be (pizzas and episodes of Friends etc) so bad that I leave after one day.
So it looks as it may have to be the slowboat from Louang Prabang to Houayxai staying overnight at Pakbeng. The boat leaves from the boat pier behind the Royal Museum tickets cost 88,000 kip to Pakbeng, where onward tickets can be bought for Huay Xai fore about the same price
Accommodation in Pakebeng it looks like a choice between Donevilasack Guesthouse or the Bounmy Guesthouse.