In my travels in the States I found that if you can get away from the bland corporate stuff - shopping malls and Starbucks, it always improved 110%.
In my experience, you have to go looking for it, but when you find what I call the 'real' America, I.E towns with a high street that has individualy owned shops and bars, and where they don't mind if the paint has chipped a bit, or have to say fake sounding greetings when you enter, it's always been great.
The other thing that's really good about Americans is that they generally have this 'can do' mentality. I guess it stems from the days of pioneers.
Instead of talking about doing something for ages and then allowing it to sputter out, they'll talk about it for as much as is necessary, and then go off and actually do it - usually at full throttle.