My knowledge of the area is about 6 years out of date, but I used to work at California Sports Center.
I definitely recommend checking out Cal Sports Center. I'm a fan of their general philosophy, and all of the coaches I worked with who I know are still there are all excellent.
Twisters is definitely worth checking out. If Alan is still running things then it would be hard to do better. Great guy, great philosophy, excellent technical eye.
My old roommate coached at Airborne. Their DP program is a bit intense for my tastes, but produces some fantastic gymnasts. I don't know much about their xcel program. I just texted the roomie to get his thoughts on Airborne Xcel, will update when I hear back.
As for Gold Star, I have no idea. Don't know the coaches, don't know much about the program.