Welcome to the Key Largo!
First, I do not believe there are any all-inclusive facilities here, like in Cozumel or the Caribbean, that include lodging, meals, & diving. Expect to pay about $80-85/pp/trip with most of the operators (slightly less if booking multiple days of trips). All trips usually include tanks and weights. Everyone runs two-tank trips every morning and afternoon, and sometimes one-tank night dives.
The following hotels have dive operators directly on their premises, or are a dive-resort:
Marriot/
Pirate Island Divers
Amy Slate's Amoray Dive Resort.
That being said, there are hotels at or near almost all dive ops and marinas. Here are a few examples:
Rainbow Reef boats are docked behind the Courtyard Hotel.
Sea Dwellers boat is behind the Holiday Inn.
Ocean Divers is next door to Marina Del Mar and ScubaDo's boat is next to their boats.
Horizon Divers is next door to and in between two hotels: Courtyard Hotel and Key West Inn.
Key Largo Dive Center's boat is at the marina next door to Key West Inn.
Every dive op works with more than one local hotels to get their divers the best rates (better than if you call on your own).
So I recommend you contact the dive operators to see what multi-trip packages & accommodations they can set up for you.
Feel free to let me know if I can be of any assistance. Happy Diving!