We just returned from the Fort this morning(actually left yesterday, then drove straight thru to Houston)
We rented a cart and loved it. Hubby thought it was crazy at first that I was willing to pay that much for it, but by the end of vacation, he saw the light!
It worked out great and I would definitely get one again, even if it meant cutting the budget on a different item. The kids thought it was fun just to ride around on it--and of course my 16 year old loved driving it!!!!