I'm a castleman and this is supposed to be one of the "rah-est" colleges, along with Hatfield. The vast majority of people I know are not in the slightest bit rah, although there are, of course a few who are, but in the main the rahs keep themselves to themselves and are generally nice people, if a little cliquish. This would be the same at any university, and if it wasn't rahs it'd be jocks or something else. To be honest, I've never felt excluded from college life because I'm not rich/precocious enough, and 99% of the people here are really nice, including the rahs. Don't let the preconception that Durham (castle especially) is a snobbish institution put you off applying. I was a little worried the weeks preceeding arriving here that I'd feel out of place and not enough of a public schoolboy (I went to a state grammar) to fit in, but within minutes of my parents leaving me I knew that this was all stupid. Yes, we do do lots of "posh" things, like having formals and balls, but we also have fancy dress ents and all-college bar crawls, which are quite the opposite. At no college is there a requirement to go to any of the formals (except perhaps parent formal, but if you really wanted to get out I'm sure you could), but half the fun of doing the 'posh' things is that it's just really an excuse to get drunk and have a good time wearing nice clothes. We have formal twice a week, which doesn't cost anything extra, and I figure that these are things that you're never going to get to experience anywhere else, and they're part of what makes your uni experience unique. I really like going to formals, I've only missed 3 ever, but I also like rock'n'roll music and go out with my friends to various alt/rock events or bars regularly. If you're more into other types of music (especially cheese) there's plenty of place to go too. You could do your entire degree and not go to one formal event (except for matriculation and graduation) or feel in the slightest bit rah, or you could go to all the events you wanted. I figured I'll never get this chance again, so I make the most of it.
One last thing, don't be put off by the fact that the open day is full of people who talk like 'tim, nice but dim', most of them won't get in for that precise reason, they're nice but DIM. Most people here are really nice (even, admittedly, some who go to Hatfield). If you're in a hill college, I doubt you'd even see a rah, except perhaps if you decided to frequent their haunts on saddler street and near elvet bridge, being mainly the overpriced coffee bars.