Hi Mark..... I was a little concerned that you want to see Cartagena on your own. There are so many vendors pushing goods at you constantly, it can get overwhelming. We took an organized tour into town for shopping and the old walled fort, and were glad we did.
Another place in Acapulco we really enjoyed was the Acapulco Princess Hotel. It it really beautiful, many outside restaurants, waterfalls, flamingos, and is right on the beach. It is quite distance from the port, out by the airport, but well worth seeing. Panama Canal is our favorite cruise, have a great trip!!