if you have limited dive experience i would go with Mana divers.
keep in mind, MOST dive boats don't offer a beginers dive in the AM (best time) when you call, ask! (most are "advanced" in AM, then run a PM boat for beginers) Mana does offer an AM beginers dive. we went last oct. freshly certified and they took good care of us. they don't have the biggest operation, but they do a good job of taking care of clients. they will also take the boat out with 2 passengers! (if boat is not full, they go out anyway!)
small boat+less passengers+ good service+good people= good diving!!
we checked when there, and prices for all dive operations are about the same (about$130 for a two dive boat trip, all gear included , less with your own gear)
you can also request 100 cubic foot tanks if you're an airhog (like me!) for no extra charge, but need to ask when you book the trip, they don't have them on boat all the time.
also- i don't recommend the shore dive , it's not that much less $, and you see so much more off the boat. it was a good dive w/ easy access, but it didn't compare to the boat dive!
if you choose Mana , tell Captain Mike " Jon and Amy said hi!!!"
good luck, have fun, pm with any ?'s
-me