We were on the Conquest to these ports in January. As 55+ year olds, we were also looking for something "low impact" and found the Martha Brae Rafting excursion. The bus ride was a little bumpy but we did enjoy the raft ride. It was very pleasant and relaxing. We bought some hand carved gourd vases from our raft guide.
I don't believe we would have been comfortable there on our own if we had not booked an excursion. The bus went downtown afterwards and we were so uncomfortable there, that we went back to the bus to wait.
We did some shopping at the terminal when we docked in Montego Bay. There were several reasonably priced shops inside and we felt very safe there. We did go through the terminal and armed guards to some of the shops outside and quickly returned to the terminal. We felt very threatened in that environment. Maybe we took a little too much caution, but did not want to take chances.
Just have fun.