Sierra Designs Cloud 15 sleeping bag I reviewed a few weeks back was cited by Backpacker's Editors for being a "durable featherweight". (page 86 of the 2012 Backpacker Gear Guide.) One of their "ultralight zealots" raved "It scrunches down even smaller than my puffy jacket!" For comparison they noted that the Cloud is tighter than the Marmot Plasma, their 2011 Editor's Choice pick, but not as trim as the "minimalist" pick for 2012, the Mountain Hardwear Speed 32.
Another innovative Sierra Designs Sleeping Bag, the Pyro Maniac 15/30 won accolades as the "most versatile" bag for its detachable quilt. Just insert the extra 10 oz. layer of down and take your sleeping bag down to a solid 3 season bag. At $319 for 2 lbs, 13 oz. of bag this is a great value when you consider you're getting two different warmth bags for the price of one.