hey gtc, just keep her away from the M3 if you find one! I was looking at '09s recently and dammit the test car had M-DTC and now she knows she could drive it too!
My wife is a pretty decent stick shift driver, so opting for a manual doesn't help me much; our stick shift supercharged Mini was a present for her a few years back since she'd been driving the "less fun" vehicle for the last few years (babies, dogs, etc, etc) and had always wanted a Mini. She can also be relatively agressive, loosing me if I'm tailing her in the BMW in the corners, though I'd catch up to her on the straights pretty quickly.... Even with trucks, she was seeking out the rare 5-speeds until we hit our first Land Rover - a Freelander; she went for a year on an automatic before we had the Mini and didn't seem to mind too much; she thought that an auto might also be easier with kids, or in an emergency when we needed someone else to drive.
The only thing that would keep her away would be a sloppy shifter; she find my BMW acceptable at best (and I can't help but agree), and basically refuses to drive Mercedes after trying out a few and finding them terribly vague...
My only "hope" that I can see is potentially picking up a convertible as she's not a big fan of having her hair blown around, or buying another Mini (which she's hinted at might be a good idea in another year - and it's only been gone for a month or so!), but we don't really have good space for more then two cars...
All in all, I'm not sweating the situation! ;-)