I have a little story to tell you,mom needs a vacay, about our first trip to wdw in 2004. We didn't go with family members but we went with friends. I won't go into all the messy details( and yes we are still friends) BUT we are going again in 16 days BY OURSELVES.
Basically the problems we ran into were that everyone ( each family- there were 3) wanted to do different things at different times. While this may appear to be a good thing because you aren't stuck with each other the whole time, it means that you end up waiting for each other for such things as meals together and rides back to the hotel together because you stupidly shared a rental van to cut costs. Anyway, I digress, sort of.
Anyway, my advice to you is this: only book your own immediate family's hotel, car, adrs, etc. Actually if I were you I would stay on-site and not rent a car. That way they cannot depend on you for rides. Whatever you do DO NOT get sucked into sharing a house off-site with them. If they want to share a house then they can, and just keep you out of it.
The other thing I have to say is about your dh. My dh was the same as yours - he would never say no to his mother. What I found out is that you still have to be the one to say no to her and that once your husband sees that you won't back down then he will really have no choice but to start backing you up because you are the one that, uh, you know, uh, MAKES his bed.
Everybody told us that it is impossible to have a bad time in wdw. Well let me tell you - they are wrong! and it sucks to waste time feeling mad or frustrated in wdw but we are human and we do not leave our normal feelings at the gates of wdw.
Anyway, good luck and know that there are total strangers on here who are thinking of you.
dolphinmom