I've been to a couple, but I think The Wakeboard Camp is the best. They really know how to break a trick down into small stepping stones and teach it to you without hurting you. They also have drills they teach you to help work on the fundamentals. Once you learn them, you can keep working on them after you've left. They have a bunch of instructors that take different boats out every day, so you can figure out which one suits your style and ride with him. Their prices are reasonable, too. These are the guys who made "The Book" DVD, by the way. Check it out:
http://www.wakeboardcamp.com