I'm coming over to USA for holidays with my wife and we will be mostly driving around parks in California, Arizona, Utah and Nevada. On quite few web pages of those parks I found that someone needs "Special use permit" for commercial filming etc. Considering bunch of posts on forums around Internet I'm wondering what they consider as "commercial" there. I heard bunch of stories telling you are on commercial side as soon as you set tripod there, and since this will be holidays I don't feel like having problems with park rangers or even police because of some stupid tripod. So what's real thing in those parks with being pro or being pro on holidays 
As I said it will be holidays, but cameras will be with me so there is chance to sell something after that, but getting photos to sell is not going to be intention of this trip.
Another question I have, is probably stupid for most of you living in USA, but still. Considering all those movies with 300 dead bodies/movie how bad it really is? I'm over there about once a year (usually just for week and never with some more time to go around) but never had any problems. Now I do have more time and I have quite few ideas for places to shoot mostly on evenings or nights. So how bad would it be to walk around with $10.000 worth equipment and getting photos of for example Golden gate or Las Vegas at night?
Thanks to everyone for all your help in advance already 

