I’ve explored a lot of San Diego but not much of the nightlife yet. For nightlife, there is a most obvious neighborhood of Gaslamp Quarter. That is where you need to be. Special shout out to J. Liu who has lived in San Diego for almost a decade and provided most of these recs!

Items are listed with the neighborhood in parentheses. Anything in italics is on my to-do list.

ROOFTOP

Altitude Sky Lounge ($$$, Gaslamp, Nightclub): Go for beautiful views of San Diego from the atop the Marriott hotel.
RoofTop600 at Andaz ($$$, Gaslamp, Nightclub): On the rooftop of the Andaz Hotel, this nightclub is for those looking for DJs and dancing.
Fairweather ($$, East Village, Cocktail bar): Tropical island-themed rooftop cocktail bar with a view of the Petco ball park is located inside the restaurant Rare Form.

SPEAK-EASY

Prohibition Lounge ($$, Gaslamp, Lounge): Hidden behind a door for Law Office, this lounge serves artisanal cocktails. Keep in mind, no open-toed shoes allowed for men.
Noble Experiment ($$, East Village, Speak-easy): Don’t forget to use Yelp to figure out how to find and access it (perhaps via a neighborhood stroll?). You’ll need reservations ahead of time or go on a weekday.

BAR/LOUNGE

Vin de Syrah Spirit & Wine Parlor ($$$, Gaslamp, Wine Bar): Alice in Wonderland-themed lounge with DJs & live music that serves wine, cocktails, and small bites.
Zymology 21 ($$, Gaslamp, Cocktail bar): Restaurant and bar opened for breakfast, lunch, dinner and late-night cocktails. This science lab-themed joint uses fresh, farm-to-table ingredients with all drinks served in glass lab beakers or test tubes.
El Dorado Cocktail Lounge ($$, East Village, Lounge, Music Venue): DJs, dancing, moscow mules, and a stuffed white buffalo head. Hrs are 7pm-2am daily except on Fridays, they open at 5pm.
Basic ($$, Gaslamp, Pizza, Bar): Very spacious and open but crowded for Padres games. Has pool tables and chill environment.
Saltbox ($$, Gaslamp, New American, Lounge): Located inside the Palomar Hotel, this restaurant has a nice lounge area that serves craft cocktails.
Polite Provisions ($$, University Heights, Lounge): Classy craft cocktails

HOOKAH

Fumari Hookah Bar ($$, Gaslamp, Hookah Bar): Extensive hookah flavors with beer and food.

WESTERN & WHISKEY

In Cahoots Dance Hall & Saloon ($, Mission Valley, Bar, Dance club): For the country music lovers and those who can line dance, In Cahoots is the place for you.
Seven Grand ($$, North Park, Lounge): Whiskey Bar with live jazz, a large backroom, and old timey decor.

NIGHT CLUB

OMNIA Nightclub ($$$, Gaslamp, Music venue): Huge bar and open area for dancing, DJs, and VIP tables.
FLUXX Nightclub ($$$, Dance club, Music venue): Attracting a lot of top performers, this crowded nightclub is one of the closest you’ll get to a Vegas-like club with tough bouncer, free cover for girls, and expensive bottle service.
Parq Restaurant and Nightclub ($$$, Gaslamp, East Village, Dance Club): It’s an expensive nightclub with a restaurant that gets crowded but has beautiful decorations.