Oh man I would KILL for some decent donuts! And American-style pizza, with loads of cheese and a pan crust. And, yes, decent fried chicken. I'm from Kentucky so I always get "Oooh you must love KFC!" and I have to try not to cry because gross, no.
There are a lot of places here that do American-style breakfasts, though I've never actually had one so I can't say if they do it well or not. I do miss a proper, soft buttermilk biscuit - I don't know why I haven't just made them myself.
We're getting some decent BBQ now, though there are so many different styles of American BBQ that it's hard to know what kind you're going to get.
I've never tied a milkshake at an American-themed restaurant, as I've been burned too many times by the sad, thin British kinds.