Imo, 38L is the perfect capacity for overnight or weekend trips. It's also a good size for winter dayhikes. I also have a 28L for dayhiking, a 50L and a 65 that expands to 80L, but the 38L is perfect and forces you to only take what you need. It's an Osprey Kestral 38 and fits my tent,sleeping kit, my 3 day bear canister, cooking kit, 3L hydration pack, my "necessities/first aid" bag, headlamp, water filter, and leaves just enough room for some clothing. The only thing lashed to the outside is my z lite. All of this (without food, water, extra clothing) weighs in at 12 lbs. I could get it under 10 by using my 50L and using a bear bag instead of the canister but I hate hanging at the end of a long day, plus the canister is only 1.6 lbs and I can throw my folded Z lite on top and sit on it.