old post but i will chime in anyway
i find all of lausanne's bars crowded and noisy. two that, depending on when you get there, are *less* crowded and noisy are the
Bar Tabac on rue beau sejour
and, not too far off, the
Standard Cafe on Rue de la Grotte . I used to try one then the other depending on the crowd situation.
Wednesdays and Thirsty Thursdays are out at the Standard as far as crowds are concerned but the Bar Tabac seems to be slightly less crowded on those nights.
I also like the
Cafe des Mousquines but I'm not sure what the new policy is (whether you can just have drinks, or if you have to eat there). From there it is a short walk to the Parc de Mon Repos.