Places you're allowed to mind are libraries or coffee shops (if you buy a coffee), and that's pretty much it. Otherwise you could find office buildings with lobbies and ask the front desk if you can take some quick photos. Or just be quick if there is no front desk attendant.

California Coffee Bar or Anchor and Anvil both have cool vibes, you'd have to go at a slower time if you want a better selection of places to pose and I'd probably still ask if it was cool but I doubt they'd care as long as you don't take pictures of anyone else haha