I've not traveled all that much (well I have, but always to the same country ) but Americans have always been super, super friendly and welcoming, especially when they hear I'm from the UK. Just striking up conversations, being ready to help out, women hitting on me, all sorts of stuff. Funnily this was least true in New York because I guess there it's perfectly commonplace to have people way the heck more foreign than "Basically American with a different accent", but Missouri and Rhode Island and Montana and Washington State people are all incredibly friendly and engaging and it's really sweet.

Although Bozeman is absolutely filled with Brits so that may not last long for me there.