There are no waitlists for any electives. This includes tours.
These sessions are held at the Rosen Centre, directly across the street from the Orange County Convention Center. When you arrive on-site, you can go to the door of the Workshop, Masterclass, or MTPL, and if an attendee doesn't show up within 15 minutes of the beginning of the session, they will sell you the seat at the door.
For tours, please check with the registration desk on-site the day before the tour to see if a spot has opened up.