if you want 'classic' pure luxury, in a (renovated) old-classic swiss luxury hotel and a wonderful garden (great Sunday brunch outside if weather conditions allow) 2 walking minutes from the lake of Zurich: Baur au Lac. For Diner in the luxury Restaurant you will be asked to wear a jacket and tie.
The Widder will be your choice if you are interested in a perfect modern 'futuristic' luxury hotel inside the walls of several of the oldest houses of Zurich. The Widder is owned by the UBS (Union Bank of Switzerland).
Both hotels are very central in the heart of Zurich and in walking distance from all shopping (Bahnhofstrasse = Zurich's fifth avenue - check the limits of your and your wife's credit cards first) and most sight-seeing places.