My daughter went with a 9.3x62. It fits her well and is easy for her to shoot, both of which inspire confidence.

Just my two cents worth.

Dave

When I was with the ex-wifey, her and I took a trip up to Sitka alaska to visit my parents for a few weeks. Went out to the range with my dad and her and brought out a few fun guns, along with my Sako A3 .375. She asked if she could shoot it, so I gave her all the pointers and let her have a ring at it, and although it didn't fit her she got bit by the big bore bug. So I built her a .375 (H&H, by the way) off of a P17 enfield, and the horrid woman ran off with it when we got divorced. However I have noticed a few things about her when DG rifle shopping.
-As it's been mentioned, if it fits her well, she's gonna shoot it and want to shoot it a lot, and most likely get really good with it
-As far as my ex goes, she liked "pretty" rifles, the ones that you cringe to take out to the field. This was probably just her though.
-They do have a smaller frame and tend to bruise easier, unless if she's comfortable don't throw a .458 Lott at her and tell her it'll be fun and ruin everything. Learned that on our second trip to the range.

I dunno if that contributes anything but just a short rambling. My new girlfriend is terrified of firearms at the moment. Bummer for me!