Sorry OP, but my thoughts probably aren't what you want to hear. I don't care what age (although K is better than 5), when you take your children out of school for something other than a family emergency, you are teaching your children that it is okay to "bend" the rules a little. For most school systems, January is the beginning of the second half. Get off on a good foot, get your bearings under you and all that good stuff. No, mommy is going to take care of everything and take us away from this for a week of fun and frivolity because she thinks it's "important". But hey, mommy can fix everything, can't she? I guess that's why you hear people who are being led off to some place that they don't want to go calling for their mommy because mommy can fix everything.
There is a time and a place for all of us. If it's work, then be at work. If it's school, then be at school. And if it's vacation, then be at the most magical place on earth.
But those are only my thoughts on the subject.