I second the mini-golf. My son adores Winter Summerland.
You could also go to DTD for some ice cream at Ghiradelli, or maybe a movie - or how about DisneyQuest?
What about playing a little air hockey at the arcade in your resort if they have it. My son and I have been doing this - tradition whenever we see air hockey tables when we travel.
Simple fun, not a fortune, but good memories and good fun.
Not sure what resort your at, but maybe go walking together, rent a little boat together, or rent bikes.
The pool can be fun too - for your time, playing a game or just goofing off, towel off and go grab lunch together.
I honestly think just the "one on one" time really is what makes it special, no matter what you choose to do
