With Integral Designs and Valandré (a French company that is a relative newcomer to the U.S. market) you get into real semi-custom bag territory. In the all-mountain category, Integral Designs offers the XPD00 Appalachian bag ($370 and up, depending on options; www.integraldesigns.com), a high-quality bag roughly analogous to the Swallow. Valandré's deal is the incredible precision with which the bags are made, resulting in a bag that "fits" like no other. For cold weather, check out the Shocking Blue ($695; www.valandre.com), rated to minus 13 but capable of going much lower. An incredibly beautiful, well-made bag.
In short, none of these gear makers' bags will let you down. It's a matter of price, style, temp rating, and fit. And keep in mind the bag in my gear loft that's gotten the most use in recent years isn't by any of these folks. It's a light Marmot bag in a model that's no longer made. Rated to 32 degrees, weighs about 20 ounces. Check out Marmot's new-edition Hydrogen, complete with a 30-degree rating and weighing in at one pound, five ounces ($309; www.marmot.com).
For the ultimate sleeping-bag encyclopedia, check out Outside Online's all-new Sleeping-Bag Buying Guide.