I assume you've got an FAA PPL or sorted the obvious and made the arrangements (see the message at the top of this group).
If you're doing 100 hours +, I hope you're there for several weeks... In which case, you can get around a LOT.
There's so much to see, if you're going to be flying a lot. You need to look at some of the old threads (dig back in this group).
The boneyards are certainly worth a visit - make sure you pick one where you can fly in.
I've flown in several parts of the US - particularly all over Michigan, Florida, and California/Arizona/Nevada.
My immediate first choice every time is "out West" - there's so much fabulous scenery there. Anywhere from Colorado, over the Rockies, around Utah, and out to the West Coast is fabulous. The distances are large, so plan for some L O N G legs.
The longest I could handle in one go was LA to Grand Canyon, about 3½ hours in an Arrow. If you're doing 100 hours + then that's a drop in the ocean.
You do need to be aware of US weather - it can be very good, and it can be very hostile!