I find the beach is usually great for this. They don't have to be people you know personally. Also if there is a park near a school - Frosty gets to meet primary school kids this way and some teenagers that use the oval for sport. On lead - very closely supervised. And our dog club recommended driving to your local shopping strip and sitting somewhere with your dog and seeing what happens. Need lots of treats, so she associates the place with good things, and you can vary the concentration of people by starting on the edge until she's comfortable.
Cricket and football games are also good. Do a couple of laps around the oval with the dog. Lots of people will say hello. Especially if you have a couple of cute tricks to show.