Have you talked with the school? We pulled DD in kindergarten over Halloween for Disney and she missed 4 or 5 days. Her teacher was fine with it. We are planning on doing the same thing this fall (second grade) and I plan to talk with her teacher about it ahead of time and come up with a plan for make up work if needed. Also check your school attendance policies to be safe.
It doesn't bother me in elementary school as long as my kids are doing well. I am not about those crowds at peak time. Yes it's Disney, no it's not an educational trip backpacking through Europe, but is quality family time and absolutely worth it for me. Middle and high school may be a different story, but we'll cross that bridge when we get there!