After many years of backpacking, I now realize I spend as much, or more, time on my back, in a bag, as I do walking, fishing, and climbing. This personal reality has resulted in my favorite pieces of gear to become the Western Mountaineering bag, (of which I have two, the Ultralite regular, and the Versalite long) and my Exped Down Air Mat 9 (DAM). I purchased both bags used (yuk! "Isn't that like sleeping in a motel where they don't change the sheets"?) The Ultralite is rated to 35 degrees and REALLY confining ( I am 6-1/2, 190# with size 13 feet). I used it last weekend on Santa Cruz Island, and at 38 degrees, with no long underwear, I started to feel a tad chilled, so the rating is right on. When the coastal evenings warm up, I use it as a quilt on the DAM to minimize the confinement. I just recently acquired the Vesalite and used it once last year at Cottonwood Lakes. Wow, what loft! The weather pattern was rainless, so I left the tent at the trail-head and slept underneath the stars on a breezy evening in complete comfort.
I switched from the Thermarest Prolite to the DAM three years ago and have used it ever since. To counter the increased weight and bulk, I now take less clothes, more concentrated, quick cooking foods, and weather/bugs permitting, no tent.