This is going to vary largely on where you live, since each college has its own housing system. There are also two option available: residence halls and apartments. In general, first years live in the residence halls and second years and above live in the apartments, though there are exceptions to this. Rooms usually have a table (and sometimes a bookcase), a chair, a bed with adjustable height, a chest of drawers, and some type of closet space. The size and arrangement of all of these things vary somewhat between colleges, however. The best way to know what the rooms are like is to just visit the campus and there are some events where students let you see their rooms (or look at the rooms during orientation).
REVELLE:
Sorry, I don't know anything about Revelle's dorms, but something to consider about Revelle is that it's in one of the far corners of the campus. If you have a class in one of the far lecture halls (Warren Lecture Hall is a popular one) it can be about a 15 minute walk to class. Revelle does, however, have a lot of the science labs and some of the science lectures, which can be a benefit if you're a science major.
MUIR:
I lived in a triple in the residence halls (Tioga), and the rooms were fairly decent sized. It was nothing like the horror stories you hear about the size of dorm rooms (though other colleges may differ). There was room to hang out with friends even when your roommates are there. In Muir, you have a suite with about ten students of the same gender and you share a bathroom with your suite. On each floor, there are four suites, one on each corner of the floor, and there are three lounges (two the far sides of the floor and one large one in the center). Two floors consist of the a house, which are connected by a spiral staircase and have their own HAs. The view from Tioga (the upper floors, at least) is one of the best views of the beach from any of the dorms (especially at sunset). I didn't live in the apartments, but they just built a new apartment building in Muir.
MARSHALL:
I've been in a triple in one of the Marshall dorms once, and it was much smaller than the triple I had in Muir. I lived in an apartment (uppers) in Marshall, and my double was about the same size as my triple in Muir. The way I describe the size to people is that while I was doing stuff at my desk, my roommate had enough space to comfortably hula hoop (one of those big, exercise hula hoops) and watch TV. The Marshall upper apartments had two doubles and a single, a living room (with a couch, coffee table type blocks, and a couple sofa chairs), a balcony, and a kitchen (with dining table and chairs). There wasn't a lot of counter space in the kitchen, so we usually used to table as extra space. They had a vacuum in the apartment for our use and provided trash cans and recycle bins (like they did in Muir).
Muir and Marshall are both pretty central in their locations, which was nice.
ERC:
I've never lived here, but I've heard that their apartments are pretty nice, though my friend said that his room was a lot smaller than mine freshman year. I've been in I-House (international housing), which has pretty nice and spacious apartments. The Village (transfer housing) is also in ERC, which is open to undergraduates through a different application process.
WARREN:
I've lived in one of their apartments, and the rooms are much smaller than the rooms I had in the Marshall uppers or Muir's ResHalls. Standing in the middle of the room, you can easily reach both beds, which you couldn't do in the Marshall doubles because the rooms were much wider. Also, when I got to the apartment, both drawers were in the closet, which wasn't big enough for both drawers so you couldn't open both drawers at the same time. I much preferred the Marshall uppers to the Warren apartments, although the kitchen in Warren was larger with more counter space than the kitchen in Marshall.
Never been in the ResHalls, sorry.
SIXTH:
I lived in the Matthew apartments, and they were pretty much like the Marshall uppers. I was in the sixth apartments a couple of times, but not enough to notice anything in particular about them. I've never been in the sixth ResHalls. Something to think about with the Sixth apartments, though, is that they are in the middle of nowhere. They're on the far side of campus, and they're not very conveniently located to anything.