Where to get a houseboat next summer?

Me and my friends were looking at renting a houseboat for next summer (2005) for about a week. Everybody seems to go to Lake Powell, but I hear the water's bad there, and we want to party AND ride alot. We're looking into it now because I hear you need to get in about a year in advance. Anybody have any suggestions about where to go, or even better specifically who to rent from? Hopefully in AZ, NM, TX or somewhere in the southwest.