Speaking of high priced motels; big cities can be expensive, especially in places like San Francisco or NYC. I have had very good experiences with Youth Hostels (you don't have to be young). Here in California, they are usually located in decommissioned military barracks, lighthouses, or donated large homes. Most have private rooms, as well as the typical dorms separated by sex, so you can stay with your wife. They are usually about 1/2 to 2/3 the price of local hotels.
I also agree on the National Parks Pass. If you see more than 6-8 parks it will pay for itself. You will still have to pay for state parks, however.