Another vote for BlueWaterDivers. Brent, and Capt. Marval run a good op.
I'm not sure that any OP is going to let you burn a tank on a shallow reef dive. Every one I've talked to allows 60minutes BT. They have schedules to keep, but if you could find some other divers, and get the entire boat for a day, then you could likely get max bottom time. I can go 90 minutes easy on an AL80 on a shallow reef, and that is not going to work for a DiveOp that is running two trips (four tanks).
We stayed at Ocean Pointe. They are nice Condo's south of Largo. These are a in the $150 per night range, but roomy and comfortable. I did a write up on them a while back (8/2005 maybe) you can likely still find it. We also have stayed at Marina Del Mar, Brent booked us a room, and it was under $100 per night. The pool is great, the rooms were a bit outdated, but clean, and had microwaves are refrigerators in them which is nice for essentials like BEER
I'm not sure Blue Water Divers is setup for overnight gear storage. That was one thing I like to see in an op if I'm diving them for several days as it's nice to not have to drag gear around between dive days.
I should also add that this topic comes up a LOT. I've responded at least a few times to this exact question in the past two or three months. You like don't even need to do a search, just go through a few pages of Conch listings, and you will see many questions and recommendations for Largo DiveOps, and accomodations.