Thanks for your reply,
Well, see the thing is, the schools in DC emphasise the fact that it's located in DC for reasons I'm sure you know (as a capital city, concentration of politics, diplomatics and internship opportunities regarding them etc etc) and I have to say it makes sense. Also, I've been to Washington once (not to any of the schools though, unfortunately) and I really quite liked it there. About St Andrews, I don't have much clue except for the fact that it's hogwarts and it has a beautiful school/campus. I'm planning to go to the open day on the 11th, and hoping to find out more about it.
So, regarding the environment, I might have an answer in april but to be honest, I don't really mind where I study, whether it is in a big city or a small one.
The thing I'm unsure of is, exactly how good is StA for IR? I mean I was frankly disappointed of StA's website on IR, whereas GW has a dedicated school and clearly seems to be keen on it. It's a stupid thing to compare, but then again, if it had a strong programme, wouldn't its website reflect this fact?