I've been looking at the Osprey Kestrel 38 myself for a daypack that can double as a minimal overnighter pack. Have to try one on and decide to pull the trigger or not by this sunday (REI member coupon expires)....
I've had a 2000 cu in / 32 liter Camelbak (Alpine Explorer) and I didn't think it had enough room for me for an overnighter, especially since I don't have a lot of tiny ultra-light gear. I ended up getting a Falcon-II (1500 cu in / 25L) and while I love the bombproof, organization, and modularity/expandibility, I'm starting to think that I might be happier with a more comfortable pack that carries weight better. At least for the normal type of hiking activities I do. I could expand the Falcon and make it work for an overnighter, but it's just not the most comfortable pack for long trips though. So I've been shopping around and have narrowed it down to an Osprey Kestrel 38 or Talon 33 (Atmos 35 would have been nice size, but I want a top loader this time). Right now leaning towards the Kestrel for the internal frame, little extra room with not much gain in weight, and slightly better fabric and a few other features. The only things I'm worried about is if 38 liters is too big for a daypack, and if having a zippered opening on the bottom of the pack is the best of ideas.
http://www.ospreypacks.com/detail.php?productID=127&colorCode=698&tab=description
If you have an REI or some other outdoor store near, it's a good idea to just go in and see what fits you the best (be sure to walk around with some weight in the packs you try on, as hikeeba said). :thumbup:
I've come to learn that these observations are pretty spot on :thumbup: