+1,000,000 on QUARTZ...
If you get an automatic (or God forbid a manual wind), she'll always be complaining about how the "battery" keeps dying. Also, avoid obscure brands (yes, Hubolt or Panerai etc. are well known around here but to your mom/girlfriend/wife they might as well be a Casio). Go with a "fashion" brand: LV, Chanel, Gucci, and the like, as most women know such brands.