Re:
I'll not be at the TdF, but having attended the ToB a few times, my advice is get to your chosen spot early, VERY early.
A couple of years ago, my son and I went to see the ToB up near Princetown. We were there two hours before the peleton came through, and only just managed to get parked, as there must have been hundreds of thousands of people in the National Park. I'm sure the TdF is going to be a lot more popular.