I haven't dove north of San Miguel but all of the wall dives were great. The south end was probably a bit better, and more advanced. The devils throat is cool, Its at Punta Sur.
Also the north end of Santa rosa wall has a lot of nice swimthroughs, Some of the guys I dove with went deep (120')at the beginning of santa rosa wall and had to come up before we reached the swimthroughs (at about 50-70').
Its all drift diving so everyone travels as a group, I haven't dove with a big boat, but I think it might get crowded down below. you really need the divemaster to find some of the best swimthroughs.
Here is a good map, but the descriptions don't do the sites justice.
http://www.underwatercolors.com/cozumel/maps/cozmap.html
I'm sure you will have a great time.
If you like italian food, try Primo's. People in my group say it's as good as Boston's north end. (I'm not a big fan of Italian)