JUST GOT BACK FROM THIS ITENERARY W/CARNIVAL ON 021911.
Cozumel is nice. I don't know how much time you have there but the X-rails adventure was great and muddy. The Liberty docked at the newer pier with the shopping area...okay but really liked shopping outside the walls.
In Grand Caymen we walked to the area of 7-mile beach. We used the entrance area near Royal Palm beach (I think that was the name of it). If you choose to take a taxi it'll run you $8 one way. The walk was easy and pleasant just to stretch out the legs. The water was still a bit cold, compared to a previous trip in Oct. 07.
In Ocho Rios, we used Phil Lafayette of Lafayette Tours for a trip to Dunn's River Falls. My wife and I liked the "get wet" tour of the falls. There were so many people there it was hard to appreciate looking up at the Falls when there were so many butts and backsides up river of you at all times.
Phil was a great tour guide. He will give you history about the island, plants as well as other little snigglets of info. Then he takes you to Fern Gully and to a nice mom and pop place to eat. The tour was $35 pp and well worth it.
Hope this helps and enjoy your trip. By the way the new docking area was not yet open as of 021711.