I teach first grade so I am speaking from an early elementary point of view. I know once children get older, things change. But here are my thoughts...
First of all, don't be afraid of us. We're people, just like you, and many of us are parents. And if you do have a difference of opinion, well, what's the worst that can happen? I know because most of us still revert back to feeling like kids when we talk to teachers it can be an intimidating experience, but try not to worry too much. We're here for the children and we care about them very much. Since you are the parents of the children we care about so much, we care about you (are respect you!) very much too.
Next, it's just my opinion but I think family time is very important and most families don't get enough time together. I also think that WDW offers some very educational experiences. Actually, I think many family vacations do. Life experiences go a long way in learning throughout life. That being said, every child is different and you should consider how your child is doing in school. School is not just book learning and there are many lessons that cannot be done outside the classroom. If a child is already behind or gets nervous if he or she doesn't know something, it may be too stressful when you come back. You know your kids best so you can determine this before you make your plans.
One last thing: when my students go away I make them a vacation journal. I just staple a bunch of pages together inside colored construction paper and decorate the cover. They write (or draw, or dictate and parents write, depending on ability level and time of year) what they did each day. If they write or dictate, they draw a picture or sometimes they put actual photos on each page. The child then brings it into school and shares it with the class. (I guess you should check with the teacher to make sure this is okay first.) I always give it back then for the parents to put away as a memento. I have many parents tell me that they love this journal. It gives the kids something to do in the evening that helps them wind down. They also work on it on the plane or in the car. Educationally, it helps because most teachers do a writing assignment each day (like a journal entry). Maybe some of you would like to make one for your kids and give it a try. I always stress that parents don't need to drive themselves crazy with it. Just do as much or as little as meets your needs. Seriously, they do seem to enjoy it.
Wow, this has been long. You can tell I crave adult conversation!
I hope I have not sounded preachy. Really what I want to tell you is that we (teachers) know you are working hard to be the best parents you can be. Don't be afraid of us. We're on the same team and we all want what's best for your kids.