Welcome to the board.
There are a lot of good dive ops in the Keys however most of the best diving is from Key Largo to the mid keys, Key West is where you go to party and maybe dive a little. 2 ops I have had recent experience with are Island Ventures and Silent World. Both have reasonable size boats- 12ish divers, run good operations and have great captains. My gear is still drying from diving with Silent World this weekend. Not sure what you are looking for in the way of "personal service" but few Keys ops supply a DM as a guide. If you want a DM/guide it's extra so don't expect to have someone in the water with you or someone to set up your gear. They load the tanks on the boat, you pick where you want to setup and do so.
Accomidations run from 5 star fancy to very basic. For me, as long as the shower is hot, the AC cold and there are no major bugs any place will do. That said, I have stayed at the Pelican (this weekend) and Sunset Cove. They are your basic 60's building, old and out of style but functional and at around $100 per night about as inexpensive as you can get. I go to dive, as long as the above requirements are met, I am happy.