Assuming your wife can and is willing to drive stick shift, go with the Cooper S model. MINI's handle unbelievably well because they are super light, super rigid, and have a very wide stance and great BMW suspension.
The MINI is a great car, the only drawbacks I can think of off the top of my head are the following:
1.) They are front wheel drive; good in the snow, but a lot of people don't like the handling characteristics.
2.) Being a MINI, it is of miniature size. Its interior room is quite limited in the trunk and rear seat area.
3.) All models are slow. Granted the Cooper and Cooper S are peppy in their own right, they should be faster considering their sporty nature in the handling and braking departments. The John Cooper Works kit is an option, but overly expensive for the 0.5 second increase you receive in acceleration. Fortunately, there is a nice aftermarket for these cars that can make the MINI's faster for cheap while maintaining good reliability for everyday driving.