nice one.
you chose quite a good time, september is when the universitys start, so a lot of towns and citys come back to life after the summer.
anyhow, as for where to go, definatly go to london and experience it, but bare in mind; its the most visited city on earth, so your just another yank at the end of the day.
Its also quite expensive, and just not that friendly in general.
however, most other places you go to, your be more of a novelty. All of the big cities have excellent nightlifes, bristol, birmingham, cardiff, manchester, brighton, leeds, nottingham, newcastle, liverpool. so take your pick really, I would aim to go places where there is a lot of histroy/scenery things to do, and then go look for the nightlife if thats what you want.
Cornwall is really pretty, laid back and slower paced, if the weather is still warm, its a nice place to be, actually anywhere on the south coast. If you stay down south around london, i suggest checkign otu brighton, a real cool beach town, and maybe royal turnbridge wells, which is just a nice 'middle england' town.
If the weather isnt so great (more likely) maybe go check the lake district in the north of england, or maybe even scotland for some stunning scenery.
If you head up north, i would recomend going to liverpool, i just lived there for the past year, and i really enjoyed it, its had a bad rep in the past for various reasons, but is really up and coming IMO. Its so different to the rest of england( in many ways, the people mainly though), a lot of nice architecture and history. and you really have to see it on a saturday night, its something else. and if your in the area you may as well go manchester and chester (a roman town).
There are also thousands of small towns, that few tourists go to, that have a lot to offer, i think you need to decide if your going do the whole country, or just part of it.
As for culture/etiquette, we are quite conserative, people don't appear as friendly as in america, but its jsut the way we are, cold approaches girls in the street is unusual, in fact speaking to anyone, unless a situation arises when you can is unusual...
A lot of bars and clubs have dress codes, and people drink a lot and get drunk, people drink to much really, but on the whole its all godo fun. most people are friendly, but there are a few knobs about, but as long as you have your wits about you you'll be fine.
i'm getting tired now mate, and am rambling on, there is so much to see and do, your never do it all, and i'm not entirely sure what to recomend, i'll try and think of some more stuff.
