I don't like to be a debbie-downer, but I think one thing to think about (and I say this as British expat), is that many of those threads about "things that I love about the UK" are either (a) looking at things with very rose-tinted glasses, or (b) making broad generalizations and apples-vs-oranges comparisons.
For example, lots of them say people are more "open minded" or "friendly" in the UK....I think this entirely depends on what parts of the UK you're talking about and what parts of the US. If you compare like-for-like (London vs NYC, or small town England vs small town USA), I'm not so sure there's so much difference. That's what I mean about the funny generalizations and apples-oranges comparisons!
And there seems to be a lot saying that there is less pressure to be slim in the UK, or that men in the UK prefer "curvy" girls, etc etc....I think that's rose-tinted. I don't think there is any significant difference on that front between Brits and Americans. They're probably mistaking the tastes of their particular significant-other for the tastes of the population in general.