My DH also has zero interest in planning or talking about any of our vacations, even the ones that are more focused on things he enjoys. I know how frustrating it can be, not being able to share the responsibility of planning or the excitement. And then there are the last minute requests and criticisms when he finally starts paying attention.
I also totally understand being married to a scrooge. I've never set aside my own money for a trip, but he writes down every penny that we spend and reminds me to find ways to save money. Fortunately, I'm almost as cheap, so it works out okay.
I have found that pushing him to discuss the trip just annoys him. He will look at basic plans if I write them down and send an email, but he doesn't become actively involved in planning and does not want to have discussions about it. He does like me to explain what he needs to pack and whether there's anything he should buy. It sounds like it might work best with your DH to focus on that.
As for his feelings about crowds, walking, etc., my DH is usually much more tolerant of things that would normally annoy him when he knows a vacation is important to me, so hopefully you'll have the same experience, but I would make sure to give your DH the opportunity for plenty of down time, even if that means he stays at the resort for part of the day or you separate at the parks. (For example, my DH goes alone to the Hall of Presidents and the riverboat at MK and has left DHS at noon and picked us up in the evening.)
Accommodate him when you can, but also remember that you are not responsible for making sure he's prepared or making sure he has the best time ever. Try to focus on how much fun you and the kids are going to have and don't put too much pressure on yourself.
