Bucharest's nightlife has a clear geography. The Old Town — the pedestrianised Lipscani grid — is the dense, touristy core, with bars, pubs, clubs and terraces stacked into a few cobbled lanes; it is the most convenient place to base yourself for a walk-everywhere night out, and by some distance the loudest place to sleep. A step away, Calea Victoriei and the central streets around Piața Romană are the more design-led scene: cocktail bars, wine bars and rooftops, calmer and better for couples. North of the centre, Dorobanți and Floreasca are where locals go for upscale restaurants and lounges, with fewer tourists and a more "going out well" feel.
The single most useful planning fact is how you get home. The metro runs only until about 23:00, so any after-midnight night ends with a ride-hailing car (Bolt or Uber) or a night bus. Ride-hailing in Bucharest is cheap and easy, which quietly widens your options: you do not have to sleep on top of the bars to have a great night, because a short app-ordered car from a clear pick-up point on a main street solves the journey home. That is exactly why the Old Town edges, Calea Victoriei and even Dorobanți all work — pick the vibe, and let the ride-share handle the distance.
Two cautions worth carrying. First, sleep is a street-level decision, not a neighbourhood one: a courtyard-facing room or a higher floor a block off the busiest lane transforms a night in the Old Town. Second, the busiest tourist lanes carry a clip-joint trap — "ladies drink free" bars and aggressively touted clubs that overcharge — so check prices before ordering, avoid following promoters, and use app-ordered cars rather than street taxis. Get those right and Bucharest is a friendly, cheap, late-running city to go out in.