The age thing is a factor. As long as you go with the understanding you may not see or do as much as you’d like, it will be okay. I found the Magic Kingdom and Animal park were the only two my kids really liked. The MGM park has some things related to shows or movies they may have seen, but much of the nostalgia stuff is wasted on them. Epcot has a few things they’ll like, but again, much goes over the heads of kids that age.
Pre-kids, I tended to go to such places with the idea to get "my money’s worth", meaning I had to cram as much as possible into one day. That doesn’t work with little kids. If that is okay, then you should have fun and make some nice memories. Just beware…they WILL want to go back!![:)]