I just got a Ultimate Luna Hydration Pack. Its made specifically for women. The shoulder harness and waist belt are designed to fit our bodies. The pack is long so it rides on the hips and doesn't pull on the shoulders. It's big enough to carry a jacket and all of your essentials.
The bladder holds 64oz, is wide mouthed and very easy to clean. I use Accelerade in it and it hasn't stained like my camelback bladder did.
I used it for two 50 mile rides this weekend and did not even notice that it was there. And it was wide enough to keep my back dry in the scattered shower I rode in, for an hour and a half!
I ordered it from REI, had to do a search to find it, it is not listed under cycling hydration packs.
Kathi