how exciting. I'd love to go to the west coast and Las vegas.
just a thought on the visa situation. IF they do ask why you've got a VISA you could say you had to get one because you submitted the ESTA with a mistake and it wouldn't let you have one.
It's only a white lie.
I filled out the ESTA for my Mum and the big dufus I was, I ticked a box saying she was a terrorist by mistake and then because I tried to submit it it got refused. Upshot was, Mum had to go to the American Embassy in London and got a 10 year VISA instead.
It was a right flipping hassle, but it could be an explanation of sorts for your VISA.
I find making lists helps when I'm going away.
Things like; get currency, buy guidebook, book tickets online for attractions; look on tripadvisor for nice restaurants to try
you'll enjoy it when you're there, just remember to have some time for you