re: 3 weeks in the USA.

I'll make a pitch, again, for skipping southern Cali for the San Francisco Bay area. SoCal is the land of the car--you pretty much need one to get around to key sights....whereas the Bay Area is so much more easily visited/toured via public transit. Better food in the Bay area, too.

In New Orleans, consider taking a swamp tour; they may seem touristy/hokey to locals, but the cypress swamp is an interesting place to visit....alligators, etc.