No one answered you on the beginner to intermediate dive sites.
The answer depends hugely upon a major variable--the currents. I have been in Cozumel with perfectly bland currents that made almost any dive site a reasonable site for a novice diver. I have been on these dives with people who had just completed their OW certification, and they did just fine.
I have also been there when the currents were ripping. Sadly, on one of those occasions, I was with a newly certified relative who had a very difficult time because of the currents--anyone would have. He did not enjoy himself, and I can't blame him.
What really makes the difference is the skill of the divemaster and the rest of the divers on your boat. In Cozumel, dives are led by a DM in the water. If you are with a group of relatively inexperienced divers and you are diving, say, Palancar Caves, your divemaster will lead you on a pleasant wall dive with some moderate weaving in and out of spectacular coral formations. You will all love it. Meanwhile, not far from you might be a group of experienced divers, and that DM is leading them through a series of tight and winding tunnels. With good DM's, both groups will have excellent experiences at the same site, and each group's experience would have been different.
Make sure you let people know your experience level when you sign up. If you go with one of the bigger companies that have a number of boats, they will try to put you in a group that matches your experience. If you go with a one boat company, they do not have that kind of flexibility. Some of the smaller companies especially tend to be sought out by highly experienced divers, and you may have trouble getting a good fit.