Just as an update, I don't think I'll be bringing much more than my DT990's with me. I thought about it after a couple posts recommending first-time meet attendees use a majority of their time to just sample new gear and take notes. There looks to be one or two HD650's coming already, so I don't need to bring that. I might consider bring the Valhalla if a bunch of people really wanted to try it out, but I don't want to have to be anchored to a table to watch over my gear.
Also, do we have plans for snacks and drinks in case of poor weather? We had talked about keeping all that outdoors if weather permitted, but I looked at the predicted forecast for the area and there looks to be a chance of rain on Saturday.