Yeah, the dorms are all different, definitely. My daughter spent two years in Mullan, which is billed as a Wellness dorm. All it means is that most of the kids are partying elsewhere and it's a bit less of a zoo than the high rises. The rooms are depressing and small there, and it badly needs refurbishment (I think it is scheduled to happen, but I don't know when). She made a major plea to move out after her Sophomore year due to a huge influx of foreign students whose personal habits were horrid compared to what most of us are used to, so the place became sort of a hell hole that year. Definitely visit the dorm DURING THE SCHOOL YEAR to get a feel for them. Freshman are required to live on campus, but after that I AM TOLD everyone moves off campus. Daughter found a wonderful apartment on Kagy and shares it with two others. New building, each kid has their own room and she at least has her own bathroom, the kids who took the bigger rooms share a bathroom. She also saved money over the dorm (that was one of our conditions -- she gets the money as if she were in a dorm, and has to cover all her costs in the apartment with it, including buying a mattress, etc.).
I remember Penn State, where I got my grad degree, the freshman dorms were WILD. So I guess it's an issue everywhere. Basically, you have to hope there is some dorm that is quieter so you can study if you want to.
I haven't heard of any bike issues, but she walks or she drives, I think she's been bicycling just a handful of times. The darn campus center is entirely pedestrian, so you don't get a lot of benefit of biking if you're living on campus. You have to lock your bike far enough away that you might as well walk.
The nice thing is there is great hiking in Hyalite Canyon and Yellowstone is close enough to go camping and wake up and see the wolves or elk, etc. Skiing is conveniently located at Bridger, but soon you'll want to HIKE to find some terrain that is not boring. The lifts at Bridger are slow! Moonlight and Big Sky are kind of a drive to do regularly, and the road there is hairy in winter without cell phone service. The town is nice and the campus is beautiful in spring and summer and not so bad in winter.
It's actually smaller than 17,000:
"The fall semester of 2007 had a total enrollment of 12,170 students. Of these, 9,518 (78%) attended full time and 2,652 (22%) attended part time."