I've never stayed there. I spoke with a guy, a guest at the Tyler State Park hostel, Newtown PA, who told me that he'd been there a couple of times and liked it. He'd stayed at other hostels in the area and that Chamounix is the only one he'd visit again.
I drove up to have a look around. It's a beautiful old building. Since it's at the end of the road past the tennis courts and stables, it should be quiet enough at night. I'm not sure of any safety issues. Though it's close to Rt. 76, it's on a hill and not right next to the road.
Plug the address into Live Search Maps and look at the aerial and bird's eye views.
Philadelphia: Chamounix Mansion Hostel - Traveler Reviews - It's definitely a hostel, but a good one. - TripAdvisor