Big,
The Desert Classic is not necessarily for people with pro aspirations. It is basically the five week course condensed into a one week period without as many repititions and ofcourse, no mental bull****. It is by far, the best week of umpiring training you will ever get.
The Arizona Umpire Academy will be a similar experience although not as thorough because it's only three + days. However, as Ken mentioned, Mattingly and Higgins were the two top instructors at Jim's School and I'm sure they'll do a great job at the Arizona Academy.
You can't go wrong with either one and since you have family in Arizona, you should probably go there. Have fun and enjoy the training - you'll have some instructors with top notch credentials. By the way, ask them about the pointing mechanic, although becareful, they might tell you where to put that finger
. Just kidding Big - take care.