I just got back from hiking in Montana. I used a TNF Terra 35. Decent bag, more straps than I'd like, but it's well designed. Durable and inexpensive.

I gave my niece an Osprey 48L when she graduated from high school. She gets all sorts of use out of it. Hasn't done serious backpacking, but she uses it for luggage or to throw around on short trips.

C.