Your children will love and appreciate what you teach them to love an appreciate. They will follow what you model.
If, by "spoil", you mean become obnoxious snobs about everything they do having to "measure up" to WDW, then I would be concerned. Children should experience the little things in life so they can really appreciate the big ones. If by "spoil" you mean that they expect to make memories with mom and dad on every vacation, no matter where it is, then spoil away.
My children are both grown and have been to WDW 3 times with us during their childhood years. The first trip was when they were 8 and 4 and
I cried when it was time to come home! Watching my kids experience Disney magic for the first time was so precious. But I also remember the looks on their faces when we took a trip to Washington DC when they were in middle and high school. When we walked into the room at Ford's Theater where Lincoln was shot, I saw realization dawn that they were standing where history happened. It was an amazing vacation.
I can almost guarantee that both of them would tell you that one of their most favorite trips was the first time we went camping when they were about 10 and 13. We were in a brand new tent and it started to rain. The harder it rained, the more the tent seams leaked til we had a mini-river along the back wall....who knew you had to seal the seams on a brand new tent! My husband told us to get ready to "bug out" and ran to the van. We broke camp in 15 minutes in torrential rain and then laughed and sang all the way home in our soaking wet clothes!
Were/are my kids spoiled? I think so....they look for the joy in everything they do and appreciate it when they are given a special gift. We can't wait to take them and our grandchildren to
DVC for the first time. We're spoiled too.....we want to keep making memories with them for as long as we can.