Bucharest does not have one nightlife, it has four or five that rarely touch. This guide is organised by area, because where you sleep decides, in practice, what your evening looks like.
Old Town: dense, cheap, loud
The highest concentration of bars in the city, around Lipscani, Smârdan and Șelari. Everything is a few minutes apart on foot, which is both the appeal and the problem: at weekends, between midnight and three, the streets are packed.
The right area if you want to plan nothing. The wrong one if you want a conversation without raising your voice.
Calea Victoriei: pricier, calmer
The axis between Piața Victoriei and the centre holds the large hotels and the places that expect a reservation. Prices run two to three times Old Town levels and the crowd is older.
In practice: stay on this axis and everything is a ten minute walk away, with no reliance on taxis.
The north: Herăstrău, Floreasca, Dorobanți, Pipera
The expensive residential side of the city, with restaurants and clubs around the lake and along Dorobanți. Distances are long and people drive: this is not an area you wander through.
Pipera sits further north again and is more offices and housing than going out. Worth knowing before booking a weekend there.
Unirii and south
Piața Unirii is the transport hub: metro, buses, taxis. Not a destination in itself, but the point from which you reach anywhere quickly.
For cheap accommodation with good connections, it is the best compromise in the city.
Two practical notes
Taxis are ordered through an app rather than hailed on the street. The price difference is substantial, especially at night and in tourist areas.
The metro runs until around 11pm. After that, driving is effectively the only option.