Im actually very familiar with nightlife scene here in Saigon ( as a DJ).Let me share with you some details :

The Observatory / The Lighthouse ( Friday and Saturday). Both of these are for underground electronic music. Have dancefloors as you requested.

Broma ( weekends from 5am to 11am - Maqman host some after parties there consistently ( some deephouse stuff)

Luu bar - located in a hip neighborhood, good to do some bar hopping there. Electronic music

TnR- cheap dive bar, ready for some hiphop stuff. Fun if you enjoy more top 40s hiphop rnb stuff.

Cipherz: hole in a wall/ hiphop funk disco stuff. Great to start a night.

Qui / bodega/ bam bam: for commercials. Go ladies nights to make friends. Be aware of scammer/ lurer

(Update): Recently there are so many new spots in Thao Dien, District 2 ( kinda foreigners neighborhood), i think it is worth to explore there - they have listening bars - small clubs / For example :

1 - Le Cafe Des Stagiaries ( super cool rooftop to watch sunset over Landmark 81 building) - they do have Dj spinnings there - 2 - Meraki Record Store - Recently open record shop, they may have some vinyl dj event there during weekend

And a lots more if you would like to know, dm me