I have a Big Agnes Summit Park 15 degree bag, and absolutely love it. Excellent performance over a wide range of temperatures, I've camped in the snow and on the beach using the same bag.
Packs nice and small for use on the bike, and depending upon my carrying capacity I either use a smaller Thermarest Guide Light pad, or the Big Agnes Dual Core wide pad (which is about 6" x 15" packed).
It's nice to be able to roll around a bit in the bag, and the other features of the bag are well thought out and work well.
With a little love and luck, we will get by.
2003 BMW R1150GS Adventure
1983 FJ45 Land Cruiser Troop Carrier