If you're invigorated by crowds and the sound of dozens of languages floating through, come for lunch during the weekday. You probably won't get a seat or a table, but you will experience the market when it's bursting with life.
Crowds are particularly intense during the weekends leading up to the holidays as well.
To be honest, we prefer something more subdued. If you do too, we recommend an early dinner at Quincy Market. Foot traffic is low around 4 or 5 p.m., and vendors pay a lot of attention to you. You can walk leisurely through the Colonnade holding your food, without fear of being jostled and ending up with cheese fries on your favorite sweater. You'll also be able to grab a seat upstairs in the Rotunda and enjoy your dinner in peace.