One traditional Zurich gem with Chagall and Picasso on the walls and all time Swiss favorites on the white linen covered tables would be the Kronenhalle on the other side of the river. There is a separate bar, the "Kronenhalle Bar" with world class barkeepers mixing some serious aperetifs and digestivs, and a bar menu including some favorites from the adjoining restaurant. Prices are quite steep, though...

http://www.kronenhalle.com