I LOVE this question.
At ACEs Conference, @Carey S. Sipp (ACEs Connection Staff) led some guided movement which was awesome. That was early one morning but many of us wished it had been available during the conference and that there were more chances to stand, stretch, and move even for a moment during the conference.
At PFE Benchmarks, they had a quiet room and some yoga mats and space to just chill out, and at Hampshire County's Road to Resilience they had a lot of stuff at the table (especially those bendy things you could fidget with) and that made a very tight space more comfortable. They also had water at every table which was nice.
Also, when people register, a nice quote or note goes a long way. At the ACEs Conference, Center for Youth Wellness had a note saying, "self-care isn't selfish" or something like that.
At the Trauma Center Conference in Boston they have chair and gentle yoga sessions at lunch in the basement but I always wished those things were right there in the room and that some breathing and guided imagery, as a whole large group could be powerful to do together.
Finally, at the NJ State Nurses Conference Kevin Hines spoke and we started with a quiet moment of silence for all who died from lethal, emotional pain. We didn't focus on how or why they died but about who they were while with us. That shared moment of silence was one of the most moving I've ever been part of in a group. So many people wept, sniffled or sat and it made me realize how rarely we are together, in silence, with honoring loved ones lost to us or suffering and how powerful just acknowledging that was in a room filled with 400 people. It made all else we heard and listened to afterwards QUITE different. If I were queen of conference planning, I would always start with something similar. It was quite beautiful. It was a reminder of how deeply personal the work is for so many of us, on one level or another.
Finally, the gifted Donna Jackson Nakazawa leads some writing exercises and workshops and is in DC (so not too far).
I'm sure it will be a GREAT conference!