Actually, you don't have to stay in hotels. You can camp in a tent for very cheap.
When my youngest was a newborn, we had huge medical bills and very little income, so we figured out how to travel very cheap with a family of five. You could buy clearance and overstock equiment over the next few months a little at a time, save a few hundred dollars and make the trip a family trip in the summer.
Here are some ideas:
Family tent: under $200
http://www.backcountry.com/kelty-eden-4-tent-4-person-3-seasonSleeping bags: Under $40 ea
http://www.campmor.com/eureka-riner...=CI&ci_src=14110944&ci_sku=45365Camp stove: around $50
http://www.amazon.com/Coleman-2-Burner-InstaStart-PerfectFlow-Propane/dp/tags-on-product/B0009PUQXWThose are the essentials. You can use a couple of large plastic storage containers to haul your own food, cooking utensils, and other necessities. Camping in national or state parks is very affordable, and you can explore historical sites along your drive. We visited 11 national parks - including an awesome night in Arches - in 2 weeks and never ate out once or paid more than $20 for a campsite. We bought groceries at local stores - money we would have had to spend at home, made sack lunches for days we had hikes planned, and had an excellent two week vacation for under $1000 - and that included our camping supplies.
We are still using the Marmot tent, REI sleeping bags and Coleman camp stove 12 years later.
If you really want this for your son, I'd recommend thinking outside the box. We can spend a lot of time and energy ruing what isn't available or what others can do that we can't, but it won't get us closer to dong what we wanted to do.
And as to your question, no I wouldn't take my kid to Stonehenge just because he'd learned everything there was to know about it. My kids learned that we functioned as a family and that high IQ didn't give them precedence over other family members when it came to spending the family funds.
