At the heart of my lightweight backpacking setup for summer is the winning combo of the Therm-a-Rest Antares down sleeping bag and the NeoAir XLite camping pad. For a couple of car camping trips, I have thrown in the LuxuryLite Cot but the pair are comfortable enough on their own, especially if you are carrying everything into camp on your back.
I generally sleep cold, so like a warmer bag, but really hate the extra bulk and weight associated with lower temperature ratings. By using a zoning insulation system together with the SynergyLink Connectors, Therm-a-Rest has not only ensured you won't continually slide off your camping pad at night but gets rid of the somewhat useless insulation beneath you in order to cut down on both weight and mass.
The 750+ fill down, 20F (-7C) Antares weighs 1 lb 15 oz., relatively light compared to other bags in this temperature range. Therm-a-Rest probably could use higher quality down to lighten up the bag even more, but the price would skyrocket as well. The sleeping bag fit is slim enough not to leave a bunch of extra space for your body to keep warm, but does give you a little extra room to thrash around. A draft collar helps to trap in warmth on those extra cold nights.
The NeoAir series of ultralight camping pads are extremely popular for a reason. The streamlined shape of the new XLite makes this camping pad almost 15% lighter than the original and packs down small. Therm-a-Rest added a reflective layer inside to help recycle your body heat, extremely useful when paired with the minimal underside insulation of the Antares sleeping bag.
The Triangular Core Matrix construction in the NeoAir XLite keeps the pad stable and supportive beneath you without sagging. The camping pad has yet to deflate on me during the night and I have been impressed by the durability of the nylon material, even with Lola's sharp toenails running all over it. The XLite does come with a small repair kit in case you do spring a leak while out on a longer adventure.
Bottom Line: If you are looking for a lightweight sleeping bag/camping pad combo for cool weather outdoor adventures, you can't go wrong with the Therm-a-Rest Antares and NeoAir XLite. The two together add only 2.5 lbs. to the weight of your pack.