I've been thinking about Exeter so I can give you a few pointers. Its very expensive for one thing, and i'd say its pretty middle class, but it still has a nice atmosphere.
Its small, but the campus is very pretty and the place is about as safe as it gets. The centre is lovely and like Angeli says there's a lot of little back alleys with some quite funky independent stores and so on, a couple of cool record stores as well.
There's not that many clubs or pubs. I've only been out a few times there and had a decent time. I don't particularly like big clubs myself, London sort that is, and Exeter has a few nice night spots. The Cavern is nice, and some good groups play at the Phoenix from time to time if you're into music. On the whole though, there's not that much variety - it'd be fair to say that its not the most fun city, and I can't imagine it attracts the type who are after that. Its the biggest turn-off for me anyway.
I imagine Exeter is better for English than Leeds if i'm being honest, its well regarded for its Arts. AAA's isn't a 'ploy', although you may get 'AAB'. I got an AAB offer for History last year, when they specify AAA. Exeter is one of the top uni's in the country, and you do have to remember that big city uni's like Leeds or Manchester can usually get away with high offers because a lot of people want to study in that sort of environment.
Welshboy: Leeds won't be as safe as Exeter, but I can't imagine you're going to have any trouble at either. Students tend to stick together don't they.