Terrasses with lake view:
For something more up market, try the hotels down at Ouchy, like the Château d'Ouchy, Angleterre & Résidence, Beau Rivage etc.
City centre terrasses:
- La Suite restaurant/bar on Petit Chêne
- Pur, restaurant/bar, Flon
- Nomade restaurant/bar, Flon
- Great Escape bar (ask for a plastic glass and go out onto the 'Place Madeleine' outside the bar)
- Etoile Blanche bar/restaurant, Place Benjamin-Constant
- Bleu Lézard, rue Enning (small, not many places)
- The Fox café/bar, rue Enning (v. small, not many places)
- Java, rue Marterey (v. small, not many places)
Shaded terrasse without view in the city centre (nice place to eat on hot summer evenings):
- Café de l'Eveché restaurant by the cathedral
By no means an exhaustive list, just a 'brain dump' of places I could think of off the top of my head.