Thank you all for your input. You've given me a lot to think about it. As a little background, we have been living in Hong Kong for awhile, and there is a
Disneyland here. It is quite small, and we have gone a LOT over the years. My older two kids have grown bored with the park here, which is probably a big part of why they aren't too excited about WDW anymore. They are currently 9 & 13. (Will be 11 & 15 at the time of the WDW trip). My younger two kids (4 year old twins) have only been a couple of times and have absolutely LOVED it, but we don't go very often because the older two don't want to go anymore. (And because they keep jacking up the prices.....). As far as the planning for the trip goes, I've done pretty much all of it, but I do ask their opinions on certain things. I think that the poster who said it's hard to maintain excitement for that long is probably right. Maybe they feel like it's never really going to happen. We have gone to Disneyland and California Adventure a couple of times when we've gone back to the USA for a visit, the last time was 2 years ago. (My profile pic). We only went for 2 days, which was definitely not long enough. I do like the idea of maybe only taking my youngest two with me, but I think my older two would end up feeling left out and sad, unless my dh took them to Universal Studios/Harry Potter World instead.
As far as my hubby goes, he just doesn't like spending a lot of money. It's already going to be an expensive trip for us, with flying from HK, and then spending a few weeks visiting with our families. To add another several thousand dollars for the WDW trip is just about doing him in, even though we can afford it. I guess we'll just see how it goes. But if we are going to do WDW, I know I'll have to start thinking about our hotel reservations etc in about 6-8 months from now. I guess until then I can cool my jets with the research and planning for a bit.

Maybe they're tired of hearing about it. lol.
Again, thank you all for your input. It is very much appreciated!
(Edited to add: Yes, I have suggested Shanghai Disneyland to my hubby several times, and even as a compromise to save money, but he has resisted. He does not enjoy traveling in China.)