It would depend on what time of year you would be traveling, and your mode of transportation. The suggestions below are assuming you have your own transportation and can get around easily.
April to September you could go right down the street and hit the beach.

There is a nice stretch of beach that my family and I go to that is free to park and has a couple of lifeguards on duty. Usually not that busy because everyone else goes to Jetty park (pay to park) Or you could go to Jetty park (this is where the people stay and watch the ships leave and wave as you are sailing past) They might have better facilities to wash off in and get changed.
Kennedy Space Center is a hop, skip and a jump from the port. They are relatively quick to get in and out of, considering that you would be arriving around 9 :30 or so. You would want to leave KSC at around 2 PM though to make sure you got back to Orlando and your flight.
The Hyatt at MCO has rooms you could get for a nominal fee and hang out there all day.
Florida Mall is close to the airport. Lots of stores and dining as well as a new Carlo's Bakery (Cake Boss Buddy) opened up in December in the food court.
International Drive is great for sightseeing and some interesting tourist attractions like the Orlando Eye, a small Aquarium and Madame Toussards all in one area.
Also, have a Wonder Works, Ripleys Believe it or Not, many dining options and lots of shopping.
Disney Springs of course.
