Down is great!...as long as it stays DRY. Once it gets wet, life becomes miserable. Having lived/hunted in western WA, I never bothered with down because it was constantly wet there. Now in Idaho, you'll probably be okay. Probably. As long as it doesn't snow or rain and get your bag wet. I guess what I'm saying is only get a down bag if it comes with a waterproof, breathable (gore tex?) outer shell.
Regardless of what bag you choose, a sleeping bag liner is a must. It gives you an extra 10 degrees of warmth and keeps you from sweating on your sleeping bag (making it...wet!) The one I like is the Cocoon Merino Wool Mummy Liner from REI. Too expensive? Then get one of the many silk liners out there. Both very good. Gives you some extra security in case it gets colder than you were expecting.
As for tents, I love the advice about getting one with a large vestibule. Very wise people on here.
Regardless of what bag you choose, a sleeping bag liner is a must. It gives you an extra 10 degrees of warmth and keeps you from sweating on your sleeping bag (making it...wet!) The one I like is the Cocoon Merino Wool Mummy Liner from REI. Too expensive? Then get one of the many silk liners out there. Both very good. Gives you some extra security in case it gets colder than you were expecting.
As for tents, I love the advice about getting one with a large vestibule. Very wise people on here.