I know the OP has already taken their trip, but I just wanted to throw my two cents in here since I just came back from a week-long stay on GC. Hopefully it will help someone else in the future, or at least give them another option.
I dove with an operation that I don't think has been mentioned in here yet, Dive 'N Stuff (DNS Diving). A quick Google search will yield their website.
Dusty runs a first-class operation and they made my dives an absolute pleasure. His two other divemasters, Jerry and Lisa, were great, as well. The most people I dove with was 7, with all the other dives between 4 and 6. If you are after a great personal experience, this is an op where you won't just be a number!