On this visit I took the hop-on, hop-off bus offered in the cruise terminal. Gives you an overview of the area. Previously I have visited Croydon Plantation and Dunn's River Falls, both very enjoyable. Montego Bay in my opinion is not one of the better Caribbean ports.
After several previous visits there isn't a lot of new things to see. This stop I walked to the library and spent an inexpensive hour using the Internet. Nice people at the library and very inexpensive. Stopped by Capt. Morgan's to get Lemonccella and wound up with a bonus of a large Rum Cake. Grand Cayman is an interesting place if you like to shop for diamonds. For people like me who love mountains and rocky terrains it isn't much different than Galveston.
Cozumel is a place where you stop when you sail from Galveston. Even though, I been there over ten times in the last four years it is still a fun and interesting place to visit. I had not planned to take an excursion but at the last minute booked the Atlantis Submarine. Thoroughly enjoyed it and when I returned home felt that now I can take that off my bucket list. Suggestion: don't judge Cozumel by the shops at the cruise terminal. Find a couple of fellow travelers (or go it alone) get a cab and split the $7 to go into the central district. Its worth the money to just people watch, plus t-shirts and other souvenir items will be much less expensive. Cozumel is a busy place and if there are 4-5 ships in port it can be hectic. Just sit back and let the others rush by, you'll still have a good time.