I think you are right that they won't be super engaged all day. I'm thinking 1/2 day tops. We're really going to appease my husband since he's not a big Disney person. The kids are interested in hands on science museums and outer space and stars (we really like to go to the Maryland Science Center for the hands on play and the planetarium show), but I'm thinking 1/2 day tops at KSC! I think you are right that we'd be able to build some beach time in Saturday late afternoon
So if I can convince my DH of my new scheme we'd have three visits to the MK during our trip-- (1) Sunday for a few hours in the afternoon; (2) Monday morning for RD for a few hours, and then Monday evening for BOG dinner and fireworks; (3) Friday for RD into the afternoon. If I'm spending so much for Disney, what's an extra $60 to get an extra day of park tickets. LOL!
I know Monday will be really crowded, but I already had that planned for fireworks in the park and figure it won't so bad to do morning for a few hours, long break at the hotel and then back for dinner and a few hours in the evening. We can strategically use some FP to cut wait times I figure. My
travel agent thought Monday would be manageable but I booked when touring plans had it rated as a 6/10 date and not a 9/10 date. I still have a hard time believing it will be so crowded on a weekday in early December!