The folks at Love Houseboat have had me as a guest several times. They have always been very welcoming, kind and provided the best possible accommodations. The houseboats (they have several to choose from) are perfect for the single traveller, couples or large groups because all the boats have furniture that can change into beds. Each boat has it's own full kitchen, tv, Internet access, bedrooms, bathrooms and some have observation decks so you have space to hang out outside too!
I can't say enough about the quality of the accommodations! The boats are all located a short walk from centraal station, or you can use the taxi service that they recommend. The boats are also a 5 minute walk from the red light district, about 10 minutes to dam square and 5 minutes from a grocery store and tons of great restaurants and bars!
The folks at love houseboat will make sure you have a home away from home each time you are in Amsterdam. The prices are competitive with mid level hotels but who would stay in a one room hotel when you can have a whole houseboat to yourself and experience one of the things that makes Amsterdam so unique?? Give the love houseboat a try, I promise you will not be disappointed!