This has probably been said already, but given how big the con has become, and how large some queues can be now, how about planning their management in advance? Like for instance, physically tracing a path using small pillars and strips, the way they do it in theme parks. This would make queues more ordered and easier to manage.
Unfortunately, queues in cons differ from theme parks in a couple of important ways.
Firstly, theme parks can have dedicated areas constantly set aside for queues. They're out of the way and no-one cares if there are people in the queue or not. At cons, we generally don't have the space for queues to be in place permanently and we also can't obstruct fire doors, entrances, exits, lifts, corridors etc. so they're generally set up only when needed and we try to route people where they won't obstruct any of the above. Of course, this is a learning process and we'll try and have things better organised for next year
Secondly, theme parks also have massive budgets for barriers etc. You'd be surprised just how much those tensa barriers cost, and the hotel only has a limited supply available - you may have noticed a lot of the queues were marked out by tape (which the con had bought) and chairs which we'd... borrowed... from the hotel
We tried our best with what we had
Using matrix signs and / or LCD tv's for croud control is something we do often at our work. Might also help out. Also using EFPrime (which was already used sometimes). Keep it up, I think you all did your best given the circumstances!
As I recall, we did try to get EF Prime updated when stage events were going to be delayed. As regards the signs, well anything is possible with enough money... if only we had some
As has been previously mentioned though, security often doesn't get advance notice of delays - we just have to handle them when they occur. Honestly, we'd really prefer if you didn't have to queue - we don't like making you wait in line any more than you like being there