We are in the process of hearing back from 21c, so wanted to throw out these other options as well.
While many of the surrounding hotels have conference rooms, many of them are not large enough to fit 70 people. For that reason, a few of the options listed below (namely Kasbeer Hall) might be a cool opportunity for scenic meetings with the whole team, while subsequent breakouts may take place at another hotel or somewhere with rooms of varied sizes.