As a veteran of LSU dorms, I think I can contribute something here ...
Does she know which building/area she's wanting to try? The newer dorms (the ones near the Rec Complex and the lake, and also Broussard) have built-in furniture that does not move. Some of those rooms may have a hard time accomodating a monitor that size because of the bookshelves mounted above the desks. The older dorms (the ones with window a/c, including the old "women's horseshoe" and the Pentagon buildings) have freestanding furniture and slightly more square footage in each room -- a monitor that size would work better in those. (The older dorms are popular for loft-building to manufacture extra space, because they have high ceilings from the era when they were not air-conditioned.)
McVoy is a special case, it has a bench desk on one side of a dividing wall and the beds on the other, with the closet doors running all along the wall at the foot of the beds; it would be all but impossible to multi-purpose a TV/monitor in those rooms, because you couldn't sit anywhere but the desk to use it, and the front door of the room is all of 3 feet behind the desk. (McVoy is popular for the closet space. It also has storage bins under the beds.)
No LSU dorm would allow a fixed wall-mount for a flat-screen TV; it would have to go on top of the desk. (There are no free-standing dressers provided in LSU dorms, except Blake. You are allowed to bring them if you live in the older dorms, but the newer ones with the built-ins don't have room.)
If you live in a newer suburban home, the odds are that the room that your DD will be sharing will be smaller than the one that she occupies now. Here is the chart of the room sizes and the dimensions of the provided furniture.
http://appl003.lsu.edu/slas/reslifeweb.nsf/$Content/Acadian+Hall/$file/Hall_dimensions+new.pdf
In any case, I definitely would NOT go larger than 26". It's hard to look at a really large flat-screen from too close up.