shore excursions/places to visit

My husband and I are going on a cruise next July. We will be going to Cozumel, Mexico, Isla Roatan, Belize and Costa Maya, Mexico. Does anyone have any recommendations on shore excursions, things to do or places to visit? TYIA!!!

Cozumel will have lots to do - going to the beach, ruins, etc.

We usually scuba. This last trip (in March), we had two 10 month olds and my elderly mother. We actually hired a driver for a couple of hours - it was wonderful! We saw so much of the island...stopped where we wanted (beaches, small ruins, restaurant). The day we stopped, there was only one other ship in port - so not so many people. Our driver stopped at Mr. Santo's beach (I think that is the right one)...it was nice...no entry fee...food/drink/chairs/umbrellas available. Paradise Beach is also popular. Both Paradise and Santos are touristy. The lady that leads our scuba tours, she recommended the following:
"Playa Palancar. It is less touristy and more Mexican. Playa Palancar has great garlic fish and kick butt margaritas. I doubt very much that they take credit cards so bring lots of cash. The prices for food and drinks is a lot less expensive at Playa Palancar. "
I believe the taxi's have been unionized...so there aren't any "cheap" taxi's from the ports :(

Costa Maya is still undeveloped - we just went to a nearby beach and hung out and snorkeled (not much to see snorkeling). We have not tried to scuba there.

Roatan - I've not been there before - but going in December.

Belize - I've been on scuba trips on cruises - but I've not actually set foot on land ;)

I highly recommend you visit http://www.cruisecritic.com/ Go to the "forums" or "boards". There are forums specifically for each of these destinations. You can see what others have done. That's how I found my private driver for Cozumel. There are lots of good boards there. Don't be afraid to book excursions on your own (instead of the ships). Your own excursion will be cheaper, but you need to make sure they are reputable and find out the cancellation policy.

Have fun!