I wouldn't say creepy, it's a bit grim, yes, but there's so much to see and do that I doubt you'll notice (or care) after a while.
Derby gets you 170s, Voyagers (and 222s), 156s and 158s, plus an occasional HST. Leicester generally gives all that, minus Voyagers but with regular HSTs; with Nottingham the same as LEI. I think freight is more common around Leicester, as a lot works into Toton, probably followed by Derby, then Nottingham. As for the stations themselves, there tends to be some shunting and movements in the yards around Derby station, but, as with Nottingham, it is fairly spread out. Leicester is quite compact with everything concentrated more or less on four lines. I would say Nottingham, then Derby, then Leicester would be my order of preference for stations to spend an extended amount of time on.