One excellent choice in a women's pack is Gregory's Deva ($249; www.gregorypacks.com). It's sized so that it can accommodate long weekend trips, or with frugal packing, trips up to five or six days (in the medium size, the bag accommodates 3,900 cubic inches of stuff). Plus it can comfortably manage 40-plus-pound loads. Features include a female-specific suspension; a hydration port; and easy access to the top of the pack, a sleeping-bag compartment, and external pockets. For some years Gregory has offered perhaps the best value in high-performance packs, and the Deva fits right into that notion.
For shorter tripstwo nights, not much longertake a look at Osprey's Ariel 55 ($199; www.ospreypacks.com). Osprey packs have great suspensions, and the Ariel is designed to accommodate a woman's frame. It's also very light, and the hipbelt can be custom-molded to the wearer.
Lastly, if you're on a bit of a budget, look at REI's near-identically named Aries 55 ($139; www.rei.com). It's a pretty straightforward top-loading design, with frame geometry to fit a woman better than its male equivalent. But this hauler's well-made and has lots of good features, such as a hydration bladder sleeve, accommodation for strapping lots of stuff to the outside, and a polyethylene framesheet that keeps sharp things from poking your gal in the back.
As I've often said, packs are like shoes: fit matters... a lot. So have her try several packs on (pre-loaded with sandbags or something) and try to get a sense of what fits best.
Pick up a copy of the 2006 Outside Buyer's Guide, on newsstands April 25, for a look at 396 torture-tested products, including the 2006 Gear of the Year award winners and an all-new women-specific review section.