I'm looking to go on a guided multi-day whitewater rafting trip on April 3-9th. I have no idea what rivers are runnable at that time in the season, which outfitters are good to go with, or whether or not they can add me by myself to make up a full party. Does anyone have any suggestions? Maybe somewhere in Arizona or New Mexico, but there are so many outfitters I don't know where to start. I would like to go somewhere you can reasonably get to from a large city because I'll be flying in alone. And I'm looking for something decently affordable because I know some of these guided trips can run pretty high.