In my school district, vacations are not considered excused absences, even when "excused" by the parent. So, a child going to Disney for a week would get marked with 5 unexcused absences. If they get more than 15 in a semester, then they can be considered for failure. Really, the theory is that if a student misses more than 15 days a semester, they really SHOULDN'T be passing.
As far as the poster taking the position that their child would be too far behind if they took a trip away without assignments being given ahead of time...The only thing I could say is that you're making the decision as a parent to take your child away on a (possibly) unexcused absence. At my school, even if I get the work together ahead of time, I'm not allowed to grade it for credit. The student should be getting zeros on all days that were unexcused. For reference, I work at the High School level, so I can't comment on Elementary policy. I do know that vacation policy is district wide, though.
IMO, I would never take my child out of school for anything more than a day. Even that is unlikely. While in education - your breaks are at Christmas, Spring, and Summer. In many, many, many other jobs you have "scheduled" vacation time - so why should I teach my children that they can take off whenever they want? A student's "job" is to learn at school - so I treat it as such.