Do any events have a waitlist option?  A group of us got into a PFS game, except one person, and I see no options for waitlist tickets.

This feature has been requested a lot, but so far no joy.  All you can do is keep checking to see if the event has become available.  

In your situation, if your one buddy without a ticket shows up with generics, and you explain to the Paizo people that he's with your group, they will probably try & fit him in.  They've usually been pretty good with trying to find folks with generics a seat.

Edit: What Buffy said. (Had this tab open too long before replying apparently)

There is no waitlist feature - you can keep an eye on an event to grab a ticket if it opens up, or you can get some generics and stop by the event in person to see if there are any open spots.

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Derek Guder
Senior Event & Program Manager
Gen Con LLC

I got to play in a playtest last year with generics last year that was full because I was early. Paizo wants to start on time, so late folks lose their spot. If there were empty spaces they took generic tickets in the order they got there and checked in. Being early helped with that. 

Advice...get there early and have a backup plan if you can’t get in.