Be careful at night in Thailand - There are a lot of LadyBoy there so you need to take extreme caution
Eh... I always figure what you don't know, won't hurt you.
Actually is it reasonably easy in the US in general?
Public transportation in the US is relatively the pits, largely because of the living pattern of suburban sprawl. If you are talking long distance bus lines, they do tend to be conveniently located near train stations.
Outside of major metropolitan areas in the Northeast and say, Portland, San Francisco or Seattle, it is assumed you have a car. In the Northeast US, there are some good subway systems and regional light rail systems, and Amtrak rocks. The Boston T and DC Metro are particularly good. The NYC subway system utterly confuses the bejabbers out of me.
Out of sheer determination, I resolved to take the light rail in LA from the airport to Hollywood two weeks ago. The remarkable thing about the LA airport rail stop is - it's not at the airport. You have to figure out that there is a shuttle bus that takes you from the airport to the "airport" rail line station, located next to nothing in particular except a strip bar. Long story short, I saved fifty dollars on cab fare, spent a buck fifty on the train, and didn't opt for the twenty dollar lap dance. It took something like two hours.
It's easier to think of things in terms of choices.
The Northeast and Mid-Atlantic
For example, if I had to eliminate a city among Boston, New York, Philadelphia, and DC. I'd eliminate Philadelphia, Boston and New York in that order, but I'd add the Baltimore harbor to DC.
If I had a choice among Chicago, St. Louis or New Orleans (depending on the route west), I'd eliminate St. Louis and Chicago. If you don't go to New Orleans, you are crazy.
If I had a choice among Charlotte, Atlanta, Charleston, Richmond, Memphis, or Nashville, I'd just ask someone to shoot me. I would skip them all and head for anywhere in the Smoky Mountains - Asheville is a great base for that, and they take more kindly to furriners than some other places you could go. Charleston is stunningly beautiful.
If you have any sort of accent, dress funny, look foreign or you have a bad habit of looking at people, stay the hell out of Alabama. Entry to Alabama is not permitted for foreigners, and we try to control what comes out of it.
Texas requires a separate visa from the rest of the US. If you accidentally wander onto someone's property, they can shoot to kill. If you are shot by a vice president there, you must apologize to him.
Do not mistake Colorado for a "mountainous" state. The eastern two thirds of it are as flat as anything you've seen for the ten hours it took to get there from anywhere. If you want a city with spectacular mountain vistas, skip Denver - go to Salt Lake City. Do not join any religions there, no matter how many attractive women they offer you. They are extremely, insanely friendly and chatty. Before you and a friend strike up a conversation, make a beer bet about how many questions you are asked before they ask "Are you a member?" After that, make a bet about whether you can actually find any beer.
You must see the Grand Canyon and Death Valley. They are unlike anything you can see anywhere else. Las Vegas is a good base for both.
If you go to San Diego, make sure you can get back into the US from Mexico if you wander into Tijuana - before you wander into Tijuana. Do not stray from Ave Revolucion if you go to Tijuana, especially after dark, and don't take a cab from the border, just follow the crowd to the bridge on the right.
There is no reason to go to Los Angeles, unless you couldn't get into Tijuana, and you really want to know what Mexico is like, and you feel like you missed out by not joining an unusual religion in Salt Lake City.
Seattle and San Francisco are actually the same city, but Seattle is cleaner and has better food, unless you really like Chinese.