You're going to have a hard time finding a package that includes both alcohol and diving. You probably can get a deal which includes both at Hotel Cozumel, which is a very nice resort - nice rooms, huge swimming pool. But the food, in my opinion, is TERRIBLE. I try to avoid AIs in Cozumel - I won't go into all the details here, but you can find my rants all over these boards about why I think AIs are a bad idea in Cozumel. But I have stayed at Hotel Cozumel, July 2012, and I ended up going out to dinner 5 nights out of 7 because I couldn't take the food. Also, if you do the all-in-one pricing at Hotel Cozumel, you'll dive with Dive Paradise. It's not a bad Dive Op, but you'll get time limited diving-- first dive to 80 feet for 45 minute, 1 hour SI on boat, second dive to 60 feet for 45 minutes, then back to the Hotel. You won't be able to dive your computer or your tank. Frankly, I think you can find a higher quality deal booking dives separately -- there are several Dive Ops that will cut you a deal for multiple days of diving with a group, and several that will provide more service and better diving (IMHO).
i go with a group every December to Coz, and we stay at Casa Del Mar and dive with Dive With Martin. Casa Del Mar gives us a group rate on the rooms and Dive With Martin gives us a group rate for 5 days of diving. Casa Del Mar does have an AI plan, though we don't use it; we just get breakfast at the Casa Del Mar (included in room price), then go to different restaurants for lunch and dinner. There are a LOT of very good restaurants in Cozumel, and for $30 a day or less per person for lunch and dinner, you can eat very well. Now the alcohol might add a lot to the budget if you have heavy drinkers in the group, and that might be reason to do the AI thing.
