In terms of a “scene” and after-dinner drinks,
I was out at a new place on the LES last week and they did last call for food and drinks at 9pm on a weeknight, just for reference.
The UWS is a residential neighborhood, so there’s neighborhood crowd not the transient bar crowd of midtown or elsewhere. Here’s a list that covers a range. There’s a bar stretch on Amsterdam in the 80s (near Prohibition & Gin Mill) which has always been and will always be bro-ish and runs young.
Restaurant bars get busy. Maison Pickle does good cocktails and is usually well-populated, then there’s Red Farm, Serafina, and Elea. Wine bars tend to stay busy all evening.
Places near Lincoln center are very busy earlier in the evening, thin out, then repopulate. Bar Boulud, Boulud Sud, The Smith, PJ Clarke’s, Rosa Mexicano (the bars at the last two are always busy). A few blocks down is what used to be Time Warner Center (variable in bar crowd), Blue Ribbon (busy), and Marea.
Everywhere is busy early evening, it’s later that all of it thins out, irrespective of whether uptown, midtown, or downtown these days. Although I’d say that neighborhood places can sometimes be busier than others on a weeknight, because people do actually live here, rather than commute in and out.