Honestly, I don't think I'd be able to stay away from the parks for so long. See if your husband's convention is offering discounted convention tickets. If not, I'd still plan to spend at least 1-2 days in a park if you can swing it.
I've always wanted to spend an entire day exploring Ft. Wilderness, but I love to walk and explore.
You can window shop at DTD, sit at the pool, see how many times you can ride the monorail before you have the entire recording memorized, rent a boat or bike at the Boardwalk, learn a skill--seriously, bring a beginner's knitting kit or a book on investing and spend some alone time learning something you've always wanted to know.
Edit: I didn't realize you're going in JULY. In that case, yeah, you might want to skip the parks and take refuge at the quietest pool you can find at your resort. You might also want to do high tea at the GF one day--it's one of the least expensive ways I can think of to get pampered in the world.