Back when my oldest two were in elementary school, we used to pull them out for a week in October and/or February. We last did that when my oldest was in sixth grade and it was too difficult for him to make up his missed work. Our middle would not have had any trouble with it, but the oldest was just not academic. Once we realized how difficult it was for oldest, we stopped taking them out of school.
Last year, we took all of our kids out for the two days before Spring Break (really just a day and a half), because we figured it was the least disruptive to their schedule and the oldest, who was a senior in high school, would miss very little (and this was the last big whole family vacation for awhile). Now, the oldest is away at college, so we're taking middle and youngest out for a week at the end of January for WDW. Middle will have no issue making up work and youngest is only in Pre-K, so he'll be fine. This will probably be the last for awhile though, at least until Middle (current sophomore) is out of the house for college and we just have the youngest.