Going to Yellowstone, Need some suggestions

RedHot thought this was worth mentioning said
3

My wife and I are going to Yellowstone National park for vacation this year. We're planning to fly into Salt Lake City drive to West Yellowstone and head south spending 7 days in Yellowstone, 3 days in the Tetons, and 2 Days in SLC. I'm hoping you all can give suggestion on what to see and which hikes to take. We'll be camping 80% of the time with about half of that being back country.

Also, I need help with a couple pieces of gear. I am looking for a sleeping bag, 35*-40* should be fine. It should be light weight and cheap. I also need a new day pack, lightweight (ultra preferred), has a space for a water reservoir and about 20-25L capacity. I have a hiking pack I just need this for day trips. I am 5'11", 210lbs, male, athletic build, if any of that matters.

Also, Also, there are 20% coupons on REI and REI Outlet if anyone is interested :-)