I'm blown away by the fact that your school is making you come up with excuses as to why you should be allowed to make the decision to take your child out of school for a few days.
My daughter is now in Junior High School and all we have ever had to do is let her school know in advance when she is going to be absent - it's been up to the individual teachers as to whether they give her work in advance to complete, or whether the onus is on her to catch up when she gets back. Now that she is out of elementary school, we will try to limit missed days going forward, but I would guess that she has probably missed 5-10 days each year to this point, just for family vacations.
But in the interests of trying to be helpful, since my experience obviously does not reflect your situation, you could try selling concepts like Disney's cultural impact on society, history lessons via the Hall of Presidents and Rivers of America, racial issues via the story behind Splash Mountain, etc.