So far, family & friends have treated us to a few nice dinners out while we were there. We really didn't expect anything, so this was a nice, and very appreciated. They've also offered to pay for groceries.
Here's some suggestions..don't know how creative they are...
check in to getting tickets to take them to see La Nouba while you're there .. a wonderful show, that everyone would enjoy at Downtown Disney west side, or any of the Disney dinner shows that may be of interest to everyone.
Check into booking an Illuminations curise for everyone..that is a great way to spend an evening and see the Epcot show..they also have cruises available for the MK fireworks as well.
Treat the family to a character breakfast of their choice..make the arrangement in advance.
Arrange and pay for extra maid service for a day during your stay. Offer to take care of the car rental.
There's lots of inexpensive things you could offer to do too...Like being in charge of keeping the towels washed every day, making breakfast and cleaning up, planning a schedule of the events you'd like to do together during your trip and arranging any priority seatings.
Or, wait until you get home and give them something special like a gift certificate for a weekend away at a favorite bed and breakfast..with the offer to watch any kids?? Or..a gift certificate to the air line they use, or car rental agency.
It is very nice of you to think about this in advance. I'm sure they will appreciate and love any gift you select for them. Enjoy your trip!