An explorer can explore in town.
I've stayed all over - I'm big on breakfast and sometimes I don't want to cook or clean. Fiesta Americana and Secrets/Sabor had great breakfast, stuff to do if you weren't diving. El Presidente was nice but'll never see my pesos again. One of the in town places has a big deal for breakfast, forget who though.
Condos are great for peace and quite, security. Some are on the ocean, others are in town.
North and South of town are sort of out on their own. South of town, dive ops will pick you up, some places you wade, some places you step off the dock. North of town is different in that I think the only pick up spot is Aldora Villas other than there are boats at the north marina, maybe they pick up people there, I'm not sure.
Dive op's - they're all there for you mostly. Valet, cattle boat - it's all there. Some AI resorts have in house diving, some like it, some hate it. There are dive ops there that will make you feel part of their family - you will absolutely become friends - one of the reasons you see so many say great things about their favorite op and even their favorite spot to stay.
What I think is the coolest thing about Cozumel is the multiple personalities. In town between 8 and 5, pure tourist. In town after 6 is completely different and Sunday afternoons are even so much better. The southern AI's or more resorty, I've never stayed north so I can't speak of that. I think you could stay at eight different places over eight weeks and have eight different experiences - it's truly a unique place.