Die Cocktailbar is a little underground lounge in Konstanz with a great atmosphere. I would go there all the time if it wasn't for the horrible service and the overpriced drinks. You can wait 15 minutes easily before being helped after sitting down, and the cheapest drink you're going to find is 7 Euros. Many cocktails run 10 Euros or even more. If you're going to come here, do it for the daily happy hour between 6:00 and 8:00 PM.
Dress Code: No dress code
Klimper Kasten is a cool little lounge/bar in the old town of Konstanz. A cool retro decor, and good music ranging from old soul, blues and funk, to the Beatles and 90's britpop are highlights. It offers a pretty standard selection of beers, and a few cocktails as well.
Dress Code: whatever
Wessenberg is a nice cafe/bar/restaurant right across from the cathedral in Konstanz. I haven't been to the restaurant, but the bar is a nice little lounge with a very nice atmosphere. Drinks are reasonably priced, but my favourite part of this is the nice "lounge" atmosphere in the bar. It's a pretty relaxed place; there is music, but no dancing or anything like that.
Dress Code: Somewhat casual. Usual European dress is worn.
Cuba Libre is a fun night club in the centre of Konstanz' old-town downtown. They offer salsa music and dancing every night, and give lessons a few nights a week, for beginners, intermediates, and advanced. The music is fun, and if you (or someone you're with) likes to dance, this is a fun night out. They have drink specials nightly, and as in most of Germany, beer is cheap every night.
Dress Code: Casual
During the semester, there are cool parties at the university on Wednesday or Thursday. It is a little bit outside on a hill and it has many platforms from which you have fantastic views over the lake. In summer, there are many disco-ships cruising the lake at night
Dress Code: no