My son played his games in San Diego, Riverside, and Orange Counties last year during the Fall Scout League season. I agree with CADad, the college coach attendance varied considerably each week. You may have two coaches out watching one day, and the following weekend there are 12-15 coaches hanging out.
Hopefully your son's team attends the AZ Fall Classic in October. I was blown away by the number of West Coast coaches on hand for that event. My kid's scout team did not attend, but fortunately he was able to hop on board with another team and had a good tournament. I know that BOF's kid had a good showing there too. If your son is not committed by the time October rolls around, I highly recommend the AZ event.