Hi SASM and welcome to the forum. I am a robotics dad and yes we parents do a lot but it is worth it! This will be my third Championship event and yes we are happy to have it in Atlanta. You and your team will have to be the judge for yourself to determine if it may be worth the money. I think the memories of it will stay with your students for a long time.
The Championship Social is held at
Centennial Olympic Park which is right there within a very short walking distance from the GA Dome. The party is of course outside but is a closed event to all that don't have tickets. There is food, soda's, water, iced tea everywhere. There is always a stage type show. There are many different events and games for the students to participate in. There is a fireworks show after 9PM.
I will let others elaborate on this but one more thing, Atlanta weather can be strange in April. Two years ago we had great weather for the social but last year it was very chilly so bring a jacket just in case.
Dave