If I buy tickets on-line at the Con, do I go to Event Registration to get them, or to Will-Call? From what I understand, ER prints them on demand, but for WC you have to wait for the tickets to be printed and packaged.
Why not just buy them at Event Reg? I plan to return some tickets, and I want to immediately buy the tickets for another event at the same time before they sell out.
In your case (return and then purchase) you'll go to Customer Service.
In general, though, if you're just filling an existing hole you can buy tickets while sitting at an event/eating lunch/resting back in your room/wandering around the downtown area/etc. and pick them up at your convenience. If you need things right away, wait in line. If you don't, order ahead.