Related to this is Social Tables (<a href="https://www.socialtables.com/" rel="nofollow">https://www.socialtables.com/</a>), a DC-based startup making some really cool event-planning software.
I built a similar (albeit not drag and drop) designer for an intranet seat-planner application eight years ago. Really like what Eventbrite are doing though. They're killing the ticketing space.