I look for a high warmth-to-weight ratio with my sleeping system, so I prefer using down bags for both winter and summer use. If you’re lugging gear on a portage or in a pack, every ounce counts. My recent favourite is the Therm-a-Rest Antares, a cozy three-season bag filled with hydrophobic down that won’t wet-out like traditional down. For warmer-temperature trips (also the most compact bag around), I’ve also put a lot of days in with my Western Mountaineering SummerLite bag—it compresses down to the size of a jar of peanut butter when packed.
For paddling journeys, I use the extra precaution of replacing the stock stuff-sack of any down sleeping bag with a dry-bag to ensure it isn’t accidentally soaked during the day’s travel. Another key to a warm nighttime sleep is a comfy sleeping pad. My favourite for the past couple of years is the Therm-a-Rest Neo-Air XTherm—a four-season pad that is amazingly thick and comfortable, yet ultra-light and compact when folded up. Once you get one of these babies, you’ll never go back.