What we've done on down days (we usually stay at Bonnet Creek)...
1. Enjoy the free resort activities (the pool parties, the movie at the pool, the magic show, the gatorland presentation, the free breakfast with games, bingo, smores roasting, etc)...
2. Enjoy the mini golf, playground, lazy rivers, water slides, ping pong, shuffleboard, and spray parks at the resort
3. Do Dinner and a Movie or Dinner and Minigolf at Citywalk (cheap double) - we sometimes split both parts, so we'll do one on one day and one on the other and enjoy some Citywalk time
4. Do a Cheap Dinner Show (with a deal) - we've done Capone's, Wonderworks Magic Show, Medieval Times, Pirates, and more - we jump on deals
5. Do a Date Night (after wearing the kids out during the early part of the day) - we've done Blue Men Group, Escape Rooms, Offsite High End restaurants for Magical Dining Month, Opening Night NFL game at a sports bar, etc
6. Spend a few hours at Disney Springs - this was finally a FAIL last trip b/c kids hated the refurb, but it has worked in the past
7. See family (we have local family in downtown Orlando and Melbourne)
8. Play games (cards/board/video) - we are a gaming family
9. Enjoy some offbeat no-walk attractions (for deals or free) - we've done the Orlando Science Center, Ripley's Believe It or Not, Wonderworks, a downtown art museum, a downtown park, etc...(I don't count
Legoland as a down day activity b/c that's a lot of walking - but we've done it

)...