The Hotel Montana in Luzern is great for this - fantastic views, great food and a cocktail and jazz bar as well.
In Zurich maybe try the Widder hotel with cocktail bar and restaurant.. you could make use of the free limo pick up and drop off service for the Zurich area, or there is La Salle in the schiffbau with a rooftop cocktail bar.
There's also the garden restaurant or the main restaurant at The Dolder Grand.
I guess it all depends on your personal preference of food, bars, price etc!
I can highly recommend both the hotel Montana and the service at La Salle although we found it hard to get served at the rooftop bar.
We haven't had the chance to try the Widder or the Dolder Grand yet.
I hope that helps and that you have a fabulous time wherever you go! x