Earthwind, yes I agree it is better not to be tied to specific days out, also much cheaper to go by yourselves and not in a specific tour.
As you say the US is full of places to stay everywhere (ranging from the cheapest Travelodges of $15 a night to the most luxurious of $100 and above) and even in the middle of nowhere like the Arizona desert you will always find a motel with a pool
A long time is definitely needed to fully appreciate the place, I was there almost a month last time and it wasn't long enough
I may just ask my bosses for some unpaid leave next year as well as regular hols.
If a group of people do it on their own, those who want to go home early can go when they please (the nearest main city airport) and those who want to stay longer can journey on.