Polynesian Resort
The Neverland Club
Location: near Snack Isle
Hours: 5pm-midnight
Price: $8 per hour per child (3-hr minimum)
Activities: Children's activity program centering around the Peter Pan theme, offering free video arcade games, cartoons, and assorted toys. Included in the price is a buffet meal and ice-cream bar, offered from 6:00pm to 8:00pm only.
Ages: Age limit is 4 to 12.
Menu: Hot dogs, Peanut Butter & Jelly Sandwiches, Chicken Filet Strips, Corn, Fries, Ice Cream
Reservations: Required by calling 407-WDW-DINE and may be made up to 3 months in advance.
We took my brother to this (he's 12 now, was 6 at the time) and he loved it. Unfortunatly Disney doesnt have much for boys in the character theming area. Boys, being boys, my brother loved that he could play video games watch movies and got 'free' food away from mom and dad.
Your DH could drop off your son at this, and then take your DD to McDonalds or something (seeing as she's 18months she'll be easier to impress)
I realize that this doesnt involve your DS and DH together, but your son would feel special, and have fun.
Short of mini-golf (which you seem to already know about) Im not sure what else there would be to do, aside from the obvious, of going to downtown disney, rain forest cafe etc...
The mini-golf at Disney is great btw. I recommend the Fantasia one. But both are equally great.
Hope this helps!