This is my experience, my theory, my view... I don't expect ANYONE to follow me
In the spring 1977 I was in 7th grade. My dad was a Beechcraft (airplane) salesman. He earned a trip to the annual sales meeting that was being held in the Contemporary Resort. We went as a family. Since we were going anyway, we brought my grandparents. We visted relatives all along the way. We went to Boise Idaho, Colorado Springs Colorado, Hayes Kansas (my gma and gpa Hays were the ones with us), Atlanta Georgia, Tampa Florida, Disneyworld, then we went up the eastern seaboard seeing historic sites inclusing Williamsburg, and Washington D.C. We were gone three weeks spanning spring break. We actually missed 9 days in school. It was a fantastic trip, and one of the highlights of my school years. My grades DID suffer. I got a C in english and science (just barely). But, I wouldn't trade it for the world! I ended up with a 3.34gpa out of high school, a 3.43 out of Oregon State University graduating with honors in Computer Science, and 3.93 out of Colorado Technical University with a Master's Degree in Computer Science. If I had not gone on the trip I would've done better in my classes in 7th grade. But... and I sincerely mean this... WHO CARES!?!
This was one of the many reasons I always knew that I mattered to my mom and dad.
I have kept my kids out of school on occasion to go on trips, do things as a family, even for a "mental health" day if I felt like they really needed it. We have traveled through Washington, Oregon, California, Nevada, Idaho, Montana, Wyoming, Utah, Arizona, New Mexico, Colorado, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Iowa, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Illinois, Indiana, Ohio, Pennsylvania, and a little of New York. Internationally various members of my family have been to Canada (all), Bahamas, France, England, Switzerland, and Turkey.
Grades are important, but quality time as a family, and "survival skills" you pick up traveling are just as important. My son is graduating this year and is already accepted in to Colorado Tech.
My theory: It's what you make of it. If you just drag your kids along and plan and do everything for them, they are probably better off in school. If you make things adventures and involve them all along the way, the learning experience is tremendous. Oh, my other theory is that it is the parents job to teach the kids how to read and to foster a reading environment. Kids that read well, and have learned how to learn are unstoppable. It's the whole give someone a fish, versus teach someone to fish thing.
AND it very much depends on your kids. We have modified as necessary as each of our 4 kids grow up through different stages in life. They are very different each requiring some consideration for their strengths and weaknesses. If I had a child with ADD I would have to work on providing a more consistent environment.