I've stayed in Luang Prabang twice and both times at the superb Maison Souvannaphoum hotel which is managed by the Banyan Tree group. This boutique hotel was once the summer residence of a member of the royal family - last time I was there I took one of the suites which overlooked the swimming pool. I understand they have a top notch spa (I am not a spa person...). Location is excellent just 5 minutes from the night market. Highly recommend this place if you are visiting this town http://www.coloursofangsana.com/souvannaphoum/index.htm