I grew up in Virginia, which meant there were always tons of places to see from a historic, scenery, and outdoorsy perspective. I had only been on a plane once when I graduated college, but my mustachian parents did a terrific job with state parks, historical attractions, and long drives. My Dad disguised looking at farms and raw land on Saturday afternoons with me as "going for a drive," which seemed very cool as a kid and helped start my real estate education. I remember thinking a 4-5 hour drive to Pittsburgh or NYC taking forever, but with DVDs our guys think that's a short day of driving.
We live in Florida now and our kids are 12 and 9, but we still focus on history, scenery, and outdoors vacations, taking a 4-5 week, 5,000-mile driving trip each June/early-July. (I can work anywhere and my wife works for the school system.) Some of our favorites:
Gettysburg -- Awesome.
Cooperstown, NY -- I had been as a kid and even though our guys aren't baseball fans, they enjoyed it.
Cog Railway, NH -- Worth the price.
Vermont, Maine -- Can never go wrong anywhere.
Mt. Vernon, Monticello, Montpelier -- I grew up around these places, but more amazing than ever with all of the interactive stuff.
College campuses -- We follow college basketball, and stopping at schools is a cheap, easy way to spend an afternoon and get the college evaluation process started early. The schools are empty during the summer, great time to visit.