Hmmm, I wasn't attracted to Durham at undergraduate level either. However, I would think that circumstances are some what different at prospective LLM level. At the point you have sort of already had your great student experience, haven't you?
I would think that the quality of the course was the most important factor and because I'm unsure about that with respect to the universities you have mentioned, I don't have much to say.
Of course, the counter-argument that is made for Durham is that its only a few minutes away from Newcastle which is a 'big city'. That still didn't clinch it for me though.