Our ship gets into San Juan at 8:30 and our flight doesn't leave till 2:45. We'd love to have lunch and do some sighteeing in Old San Juan in our "spare". What do you do with your luggage? I know that RCL will not keep it for us.
Mary, Chuck has a really good idea about hiring a taxi driver for 1/2 day. Put your luggage in the trunk and you won't have to worry about it. Just make sure you are at the airport and have cleared customs as lest 1 hour before your flight. San Juan airport can be really zooey with all the cruise ship passengers leaving.