I lived in Langland in my first year and Caswell in my third, rooms are generally tiny in both of those building (oxwich as well) not sure about the new ones because they were being built while i was in my third year. Each floor has one bigger room (16 rooms on each floor) because on the ground floor one room has been adapted for disabled students, the size of the room is therefore reflected in the floors above. you'll be lucky if you get one in your first year as they tend to put the flats of third years in the flats with the bigger rooms (i had the big room on my floor in my third year). You might be lucky though.
One thing to note is that swansea is rubbish at assigning people rooms, i had an unconditional offer as i was a mature student, because of getting an unconditional offer i should have had my first choice of accom. i ended up in my third choice at first (in two story hall designated the quiet hall) at the time i thought that the new buildings must have just been super popular until i found a friend who ended up in the new halls and he'd selected them as his second choice, and he didn't get his grades either so shouldn't have ended up there. i was lucky as they moved me after a few weeks into a room in the new building as a girl just hadn't turned up. in the flat i ended up in in langland, one of my flatmates had made a big point on her application form of saying she wantd to be in a non smoking flat and we had two greek girls in our flat who were constantly chain smoking (although since the introduction of the no smoking laws this wouldn't be a problem nowadays).
There were also stories of girls who had asked for single sex flats who ended up co-ed and really quiet people being stuck with loud and noisy people. i reckon they didn't pay any attention to the information people wrote on the forms and just picked names out of a hat and put them in different flats. i can understand that it is difficult for them to get it wrong occasionally but putting someone with an unconditional offer in their third choice while someone who didn't meet their offer gets the better accom and girls who specifically ask for single sex flats into co-ed flats is just wrong.