The ice cream social is not a buffet. It is individual ice cream cups (made up really cute, especially for the kids) served tableside with water. It is a fun thing to do and a very inexpensive way to meet the characters. My kids also loved that the restaurant revolved.
Be aware, since I see you have 6 children, we tried to make PS for 8 and were told that required a credit card deposit (no other ps's except for a select few require this for a party of 8), so we just made two PS's for 4 and it worked out great. We didn't want to leave the cc just in case we didn't make it for some reason. I wonder if they do that because they make up the ice cream treats ahead of time? I don't know. By the way, this was back in Nov. so I'm not sure if it is still the same policy, just thought I'd mention that it was back then.