She's 19, right? The hip-happening popular music dancehall and bar that is the Limmat Pal X-tra (she'll have heard of it) directly on Limmatplatz has a rather swish and affordable hotel...upstairs! I've had a look around and it's très bien (that means nice, nice). It's a little bit more of an interesting neighbourhood for younger people - and us oldies - than Altstetten and has great transport links to get her to class on time. Why not get her to bring a friend for the last night, if it's a Friday? That'd be a blast.
http://www.x-tra.ch/ (don't include breakfast, plenty of great cafes in the area, inc. the yummiest Italian delights this side of the Gottardo; PM me for more)
Treat her nicely, she'll be nervous. And she'll thank you for it.