After-dinner drinks in Williamsburg
I second kathryn's recommendations, but would add these others:
Donna: Has great drinks, a laid-back Latin-American vibe in a beautiful space. It's slightly off the beaten path, so not as crazy busy as the others already mentioned. On the South side right near Marlow & Sons. Probably my favorite right now in that part of Williamsburg just because it's hidden and the masses haven't found out how good it is yet.
Bia: Vietnamese bar and snacks in a rustic, multi-level space with a cute rooftop bar. Also on the South side.
Akariba: If you want to walk a little bit, go to this romantic, Japanese oyster, sake, and soju bar next to Zenkichi (same owners) in North Williamsburg.
Assuming you mean cocktails:
Dram - closest option, cocktail bar, very open feel, laid back, allows standing, gets loud, you may not be able to get a seat/table when it's busy
Maison Premiere - excellent NoLa themed oyster bar, fabulous cocktails, great garden space and atmosphere, a little further away and a a little more fancy feeling, gets REALLY crowded for their oyster happy hours but clears out afterwards
Post Office - cool neighborhood-y venue, excellent whiskey list