Miami is a great city. The cultural experiences are worth going down to Calle Ocho for a Cuban sandwich. The outlet malls are good as are the museums and beaches. It is worth at least a couple of days before or after any cruise from this port.
Roatan Island, Honduras is an interesting port. There is a large, new shopping area right at the pier. We found a free WiFi signal upstairs near the car rental shop. Walking into the "city" of Coxen hole takes about 15 minutes and is a great cultural introduction. (There is no need for the $5 taxi ride). We watched several boys diving off an old fishing boat and swimming. A local supply boat unloaded a pig, food and hardware, clothes washing was occurring down a lane and being hung to dry. There are a couple of Internet Cafes on the road but I did not go in to confirm availability. The Yabba Ding Ding shop in Coxen Hole is slightly cheaper than the shops at the pier. Dinner companions enjoyed the island tours and zip line.
Cozumel is a good stop. There are a gaggle of shops at the pier and an abundance of souvenirs. We walked the 3 miles along the coast to the Forum shops. Very pretty and level ground but with the heat the $7 taxi may be advisable. When you exit the pier shops, you can get in line for a taxi. Or turn left and walk about 100 yards to the next hotel to immediately catch a taxi for the same price. There is a large grocery store right before the forum shops. They were delivering their live Christmas trees so it smelled like Christmas. We enjoy looking through the groceries, house wares and decorations. This is not a tourist store so some Spanish is advisable. The tourist area is a constant "no gracias" to the unending touts. We didn't stay long. There is a McDonalds with free WiFi.