I freely admit I've never done the Grand Canyon- it IS on my bucket list! So I've saved a lot of this info on my computer yes, I am a dork!

I have done 1500 miles of the Appalachian Trail on the East Coast. One of the nest places I found on hiking and pack info is the WomenHikers group on yahoo groups. It's kind of like the TE for women who backpack.

I second that your pack and your boots are the two most important things you buy, don't skimp. You may want to check out ULA packs, and find out where your local (or not so local) Gatherings are to check out gear.

BREAK YOUR BOOTS IN. depending on what you choose, if you go full-grain leather, pour hot water in, let them sit for 30 minutes, pour them out, then wear them around the house till they dry (yes, change socks frequently). They will mold to your foot, and voila! no blisters. I tend to go the hiking shoe route, they are lighter and work better for my feet (300 miles with full-grain, no blisters but major heel pain from the weight), but that is truly personal preference.

I can't wait to hear how it goes, Happy Hiking!