I took the whole family to Cozumel last January so I could do my first open water dives. The Reef Club is basically okay, how much you like it depends on a lot of things. We have two small kids (4 & 6), so the big resort thing was kind of nice (nice pool, easy beach access, water activities, kid's club [though we didn't use it]).
It's a large resort - my wife and I joked that it's kind of like a cruise ship on land. Lots of people. Food was okay, especially at the restaurants that require reservations (easy to do, just need to do it in advance). The rooms are fine - a little small, but we were right on the beach which we loved. If you're the kind of traveler that only likes the small, undiscovered, untouristy 'real Mexico' kind of places it's probably not for you, but if you're just looking for a fairly inexpensive place to relax and dive it's pretty good.
I dove with Blue Angel and would recommend them. They were able to pick me up at one of the hotel's docks (not the Sand Dollar one) and drop me off right back after diving. Easy to get lazy with a setup like that! Blue Angel is a fairly small setup - no more than 6 or 8 to a boat; divemaster kept an eye on everyone, but mostly let you dive your own profile.
Have a great trip!
-Neil
