Barb - when we docked at Key West there was a small gambling boat right across from us. Not sure if it was a book ahead or if you could just walk on. It looked really small though.
Since you are getting in a day early I would suggest that DH go the Sterling Casino Line out of Port Canaveral. They do 2 cruises daily 11 am - 4 pm and 7 pm - Midnight. Maybe DH could do the evening one while you and your son are having the Dismeet at the pool. The number is 1-800-ROLL-7-11 My in-laws love Sterling and even took a day out of our WDW trip last year to go do it.
If you let him do this Friday night maybe he'll concentrate on the family for the rest of the cruise!
There is so much to see in Key West I wouldn't waste time to go on that little gambling boat there.
