My IL's did take my DD to WDW two years ago for her birthday. I wasn't able to go and just assumed that she had done everything she wanted to do b/c she was so excited about her trip. Turns out though, she didn't go on a single ride the whole time they were there. It was a week in November, and my MIL told her everytime she wanted to go on a ride that Grandma didn't feel well.
I think they saw every parade and every show, but they had no interest in rides or putting themselves out to go on even one ride with her. Needless to say, she's going to find out that WDW with Mommy is waaaay different from WDW with the grandparents.

These are the same people who take at least one, if not two cruises every year and who's idea of camping is their massive RV with all the gizmos and whizbangs money can buy.
I guess what I'm trying to say is that you can't force people to do things they're not interested in, and like a previous poster said, it's much better to have happy memories than ones where the grandparents were less than willing. I'd just stop inviting them for now and maybe down the road an occasion will arise that'd be perfect for all of you to do together.
Oh, and I totally understand about the visiting and reciprocation. They make loads more than we do, have no pets, and are retired. Yet they still get annoyed that we won't pull DD out of school on their schedule and fly her across the country to sit at their house for a week. Sorry, but skipping school to sit DD in front of a tv b/c there's no other kids within walking distance is not my idea of quality family time.