I know Gillespie Field quite well... it's a great airfield and you'll find less traffic I think then in Long Beach. I'll be visiting there myself again in September.
In the end, it depends on which school you're planning to train at. At Montgomery Field, which is west of Gillespie, there's American Flyers, which would be worth considering... at least I think they're still there. I myself fly with
Golden State Flying Club , but it's more a club atmosphere and in the end it all depends on exactly what you want to train for.
Whatever you decide, have fun!!
Westy