I agree with what most of the other posters have said about it being no big deal at all in elementary school. Even though I really love to go in September or November, I decided against it once my oldest hit 6th grade. For us, in 6th, grades really start to matter. Kids have to maintain a 94 average to get into NJHS, and they apply in 6th. I wasn't willing to miss a week out of school while trying to maintain a 94 average. Also, they start doing service hours in 6th grade, and missing the school baseball or basketball game becomes a pretty big deal at that age when you are on the team.
However, I think it really just depends on the school and on your child. I have friends who have no intention of trying to get their kids into NJHS, and are content with Bs and Cs. For them, it would be fine to be out of school for a few days. Most all the work is posted online and accessible online, so that makes it much easier for the child to do work while traveling. It really just depends in your situation.