Bollywood dance events in the square tend to draw a mix of instructors, enthusiasts, and curious passersby — the format is usually participatory, meaning you're not just watching a stage show, you're being pulled in. That's the pitch: you show up not knowing the steps and leave having done something you didn't expect to do on a Saturday.
Practical note: Union Square has metered street parking that disappears fast on weekends. Garage on Geary at Mason is your best bet if you're driving, but honestly BART is the call here — you're walking off Powell Station directly into the plaza. Food options are all around the square; Blue Bottle on Mint Plaza is a five-minute walk if you need to decamp and regroup.
If you've got two hours: catch the first 45 minutes of dancing, grab a coffee, walk back through and see if it's still going. It usually is.