It's been said several times but let me repeat.
Get her what she wants!
That said I have the 360 and picked up the wii last summer and gave it to my kid for Christmas. While not as good graphically speaking as the 360 or my PC, the whole family has a blast playing wii sports and Mario cart. My son and I play several games together quite frequently which imo is great quality time in when combined with the otherwise standard father son outings, projects, etc. Not sure if you have kids or not ( sounds like not ) but this could translate to time with your wife that you enjoy too ( not looking at antiques or what ever ).
Additionally, the wii has a pretty nifty browser for grabbing news, and weather...