I can speak to the South Building only -- as our convention was only in this building.
Our convention was 3 days long and (in addition to the talks) it included coffee, morning snacks, lunch, and afternoon snacks. I was impressed with how seamlessly -- and almost invisibly -- the staff kept the bathrooms tidy and well stocked, the food magically appeared and disappeared, and the food quality was surprisingly good. There were even vegetarian and vegan dishes on every buffet table -- and they were actually good!
There are many areas that are easy to overlook when everything runs smoothly, so I just wanted to say that I appreciate these things: The sound systems and projectors/screens were absolutely adequate for my needs as a participant. The tables and chairs were sufficiently comfortable. There was plenty of space to gather and be in conversation without being in the way or too far out of the loop. Staff was polite, friendly, and really good at getting things done. I am generally complaining about too much A/C in a building -- but overall, I only felt truly over-air conditioned a couple of times.
A couple of bonus items: I'm not sure if these are part of the normal experience here or if they were exceptions made for our group, but there was a dedicated gender neutral restroom and a lactation room. I'm so glad to see these things!
You did a great job of supporting the event!