What time is your flight? Most hotels have a 3:00 or 4:00 check-in time. When you figure in the time to get from the ship to the airport and the need to check-in for your flight 2 hours before departure time, how much time will you have to kill? What we've done on departure days from Disney is check out of our hotel and head to one of the local malls - there is a nice mall not far from the airport. We browse around there, have lunch, etc. before heading to the airport.
When we had time to kill in Miami after a cruise a couple of years ago - flight home wasn't until 7pm - we rented a car for the day and drove around Miami, went out to lunch, went to the mall, etc.
Just a couple of thoughts. As for the hotels, if you want to get a room, I'd suggest checking all the airport hotels and just pick the cheapest possible room and requesting early check-in.