We stay as Casa Mexicana, the place you get breakfast at when you stay at Suites Bahia. There is no beach at either so if sand is your thing, you will have to go to either the north or south end of the island.
the Thirsty Cougar is a great bar and is across the street from SB. They have live music (awesome) and I have wondered if it can be heard in the rooms. If your an early to bed type....I would ask around to see if it is an issue. the Cougar has great drinks, world class Mojitos, and huge frozen drinks. Their Ceviche is great as well. Casa Mexicana usually runs about 70 a night and you can get the best rate calling the desk directly. We have had breakfast with several people staying at SB and have never heard any complaints.
Other than diving, I want to eat so staying close to downtown is important to me. There is lots of really good, really reasonable food so an AI is a waste of money to me.
Dave (Aldora) and Christy (Blue XT Sea) are supporters of this site, so if you haven't selected your dive operator, at least give them the chance to earn your business. All the operators do something a little different so you just need to pick the one that meets your preferences. As long as you stay off the cattle boats, you should have a great experience.
Blue Magic has "Sleep and dive" packages with everything from bed and breakfasts to all inclusive so. Good prices too. I have dove with them before and can recommend them without hesitation. We will be diving with Aldora because of the steel 120 tanks next week and I'm trying to put together a night dive with Blue XTSea.
the bag drag is not too bad. If you get in late, it sometimes gets rough on the ferry over. Lots of seriously green people when that happens. Even the locals get sick. Check your airfares, sometimes it's not too much more to fly directly into Coz.
https://matrix.itasoftware.com/ will give you a monthly rate schedule for multiple airlines. If I can fly in to Coz for 50 to 100 more, it's worth it to me. Shuttle and ferry both ways and 2 hours or so each way. Bag drag is kind of fun, but there are better ways to spend your vacation. In the last week, someone posted a bag drag question and a response posted step by step details with pictures on how to do it.
Be be prepared to become addicted. I've traveled quite a bit and Cozumel is my favorite place to be. I'll be there SAturday!!
jay