[Torture]

-7 - -9 is a good range for camping in the Rockies. Definitely down if you want somethign that is compressible and lightweight.

A sleeping bag liner isn't a bad idea as well - it helps add a couple degrees of warmth and keeps your bag cleaner....the silk ones are pretty luxurious.

And of course, a sleeping pad is pretty much a requirement as well, both for comfort and the insulation they provide from the ground. Thermarest makes some good products - I like the NeoAir as it's way more comfortable than the ProLite I had before. If budget is an issue you can survive with a foam pad but the Thermarests are much more comfortable.