We never had any problem taking our kids out of school until they hit high school age. The workload involved, not to mention the school's attitude towards attendance, have pretty much forced us to stick to vacation times until the youngest graduates high school. We are able to cruise on her spring break, which falls in March, but find the fares much too high to cruise in the summer. We usually do some kind of land-based vacation in the summer months. She no longer gets a fall break, so that is out for us as well.
A lot depends on your school's attitude toward attendance. Prior to high school we never had a problem with the teachers and school letting the kids make up their school work or do it while we were on vacation. Now the rules are much more strict. If they miss more than three days without a doctors excuse they could lose the credit for the class and every hour missed must be made up in "Saturday school". Travel other than for an academic reason is not an "acceptable excuse" for missing school. While I do agree that travel does make our children brighter, more sociable, improves their self-esteem, and broadens their horizons, I don't see the point in our taking a vacation outside the scheduled non-attendance days and having them be "punished" for missing school for our vacation. So, for now, we'll stick to the spring. (three years and counting - lol)