If you want to go during Carnival, you may want to hurry on your planning before choices are too limited.
Looking at air only: PBI,FLL, or MIA to Cozumel, QR, Mexico: various dates from Feb 22 2011 to Mar 12 2011
I see nice flights starting at $453 for those dates, not much higher on some others, but all combinations with returns March 10, 11, or 12 run over $500 and over $600 - one combo with the 11th actually over $700. I don't know when you want to go but I have to select dates and airport to look at an idea so I'll play with some, leaving and returning same airport...
You could book FLL-CZM: Mar 2-9, Hotel Coz, Garden View or Pool View with Private Balcony 322 Sq.Ft, FREE Breakfast Buffet + $50 Credit: Orbitz Vacation package air & hotel for two for $734 per person including hotel taxes (Ocean view 355 Sq.Ft - $19/night more each :shocked2

THEN, use discount code
200entertain to
take $200 off of the package for two, and uncheck the overpriced Airport Shuttle Service to get it down to $634 each. Easier and much cheaper to handle ground transfers there.
So compared to $456 tickets each, that would get your room down to $50.86/night for two, including taxes, breakfast and $50 voucher.

Book your diving with whomever you want.
It's just not my kind of property so it's hard for me to guess what else you might like since it appealed to you. We picked up a physician buddy there several days on my last trip (he was almost always late

but such a likable fellow) and he said his non-diving wife really liked it there - so whatever pleased her worked for him. I asked him if the rooms were a little small, but since he was the only diver and left much of his gear in the lockers, "nope." I'm just used to larger rooms; many hotels have smaller ones tho with people doing fine.
Anyway, doing breakfast there, then lunch wherever, dinners at enjoyable places in town would be the way to go I think, and getting your air & hotel package at $634 each, you can afford to spend more than $200 each on other meals. But how does that sound
to you...??
Or you could book Casa del Mar with the discount for $599 each air & hotel, Standard Guest room - 373 Sq.Ft, and that might include breakfast buffet. It often does even tho not listed, but can't say? I think it's about a mile further from town, but - depending on where you go for dinner, I bet you'd be using cabs from either hotel - at about the same cost for either, but not that much for two people.
Or shop for Vacation packages at
SideStep - Vacations - Compare Hundreds of Travel Sites At Once, be sure to check "On Cozumel only" to avoid nearby hotels on the mainland, select "sort price low to high" and look for Orbitz links so you can use the discount code. Don't believe their location info tho, as it's furnished by Google maps and very error prone; look at the actual addresses and double check on the hotels' sites.
As far as renting a car, I never do. Cars are cheap, but Collision insurance is a must no matter what your credit card tells you or booking site tries to sell you for less. If a problem happens, and you don't want to stick around to deal with it in court, in Spanish, you will pay before you leave unless you are well covered. Some Liability insurance is probly included on rentals, but enough to make me feel comfortable would cost more. And then there is the parking challenges in town. Walk, take a cab, maybe rent a car for day to tour the island, but I don't rent cars there.
As far as Operators, I think almost all are nice, friendly, relatively safe, etc - but I like fast 6 to 8 diver boats that get me to the south reefs in hurry, more importantly get me back in a hurry after we're finished. You can start a real cheerleading war by asking who likes which on a new thread, or look around. I used Scuba Mau last time, with them rinsing and storing my gear, after emailing for prices paid in
US currency (real cash bills; I've had people read over that at times) for trips for less than $60 each including taxes and park fees. I'll certainly be returning to them, but others like others. One popular Op charges $85 for about the same thing and people keep going back.
