Several choices here, in both down and synthetic fill. On the down front, a bag that would suit your purposes perfectly is the 30-degree Sandpiper from Feathered Friends ($320 with Pertex shell; www.featheredfriends.com). It’s a semi-rectangular bag with a full zipper, meaning it’s easily unzipped and used as a blanket or quilt. No hood, which simplifies its unzipped setup. On the downside, its roomy design means a slight weight penalty with its two-pound, eight-ounce load. That’s still pretty light, though, and it’s very compressible. Feathered Friends’ quality is impeccable, too. Western Mountaineering’s Aspen ($265; www.westernmountaineering.com) is similar, a hoodless down bag with a full zip, although in this case it’s rated to 25 degrees even though it’s a few ounces lighter than the Sandpiper. Like Feathered Friends, you’re assured great quality.
For a more traditional hooded down bag, I like Marmot’s Arroyo ($259; www.marmot.com). It’s rated to 30 degrees (last weekend I used one at 11,000 feet on Mount Rainier and was overly warm!) but is fine for summer use. It’s also super light at one pound, 14 ounces, and packs down to the size of a cantaloupe. This has been my favorite all-purpose bag for about four years now.
On the synthetic front, Integral Designs’ Andromeda Strain ($170 in regular length, standard width; www.integraldesigns.com) is one of the best light synthetic bags around. It’s rated to 40 degrees but can handle cooler temps. The Primaloft fill is soft, compressible, and highly water resistant. It comes with a hood, but a full zip expedites unzipping. And, weighing only one pound, 14 ounces (it can be ordered in wider models, too), it’s very light. It should be plenty warm for your intended use. Most other synthetics weigh in at over three pounds, or are rated at temps that make a bag almost superfluous聴you might just as well carry a fleece blanket.
Hope that helps. Thanks for reading!