We knew that the four ports of call for our January 2012 cruise through the Panama Canal would be hot and humid, and we were not interested in paying for ship excursions, particularly the "adventure" ones. Our goal was just to walk around and try to get a feel for each port.
You can easily walk from the dock to the port town in Aruba, but there isn't much to see there beyond the usual souvenir shops. However, Cartagena (pronounced cart-a-hay-nya) has a brand new catamaran service from the end of the dock to the "old town," with its narrow streets and Bouliva Plaza with its free gold museum. The trip costs $5 per person round-trip and takes about 15 minutes each way. An excellent independent excursion.
Fuerte Amador is a great disappointment. If you don't want to take a cab to Panama City (and note that museums usually close on Mondays), you can take the tender to the dock and walk a little. The docking point is at the end of a 5 km sea wall constructed at least a hundred years ago to protect the Pacific entrance to the Canal. There isn't much of anything to see there except a few run-down shops and restaurants.
Cabin 305 on the Baha Deck is immediately off the hall where the stairs and elevators are, but noise was never a problem. The room was comfortable and the balcony a nice place to sit. The only caution is that the showers are tiny.