As much as I hate to say it, I would be against mailing out badges and here's why:
Most conventions don't because if they do, people have months (at least weeks) to make copies of them. Loads of conventions suffer from people making copies of badges and quite simply, only giving them a day or two to make a copy is far better than giving them plenty of advance notice, and all of their 'sources'.
A comment on badges though:
Make the badge number MUCH larger. Also make it bold black on a white background. I would suggest taking up 1/8th the size of the badge and have it on front and back of the badge as they are printed on both sides anyhow.
This would make it 1000x easier for people to report problem causers.
Security suggestion:
See about bringing in 2-3 police officers, if anything just for saturday from noon til 3 or 4am... most of the time if you are a npo, you can get them for around 15$/hour per officer.
Signs:
I would suggest more signs as to what the lines are for, for instance pre reg A-K and L-Z. Write on the floor with gaffers tape marking like a pedestrian's cross walk. I witnessed dozens of people cutting in line at the hotel's check in line. I witnessed hundreds of people who were clueless about the pre reg line.
Cosplay: and main event room events suggestion
The hotel has one or several channels that they can show a video feed on, why not take advantage of that option... display more than just the convention schedule on it, during cosplay or sell out events, have it displayed on there. This would be for everyone who had a room in the convention hotel. Perhaps record the mega popular panels, and play them on one of the hotel's channels and posted replay times... Having dealt with hotels in the past, they usually have this option, they don't advertise it, and they often charge a little more for it... BUT you will have overflow options with this!
VIP badges:
I may of just missed seeing it, but offering vip badges for people who were willing to pay for them, and limit them to so many people. If the admission for the convention will be 50$... 200$ is a reasonable price, and tons of people are willing and able to pay that! Vip badges for people who don't know, allow them 'no lines' for main events and autographs. They still have to wait to get into regular panel rooms though
Late night programming:
While lots of people are sleepy and goto bed early, there are tons of people who are still awake at 3am... why not have panels that go beyond midnight? (at least until like 2am) You don't have to save that time for adult only programming... it can be family friendly programming as well.
Water!
I know saturday is hectic, but maybe the hotel should be informed, they need to assign 1 person to nonstop (or very regular) water refills from 2pm until at least midnight? I would say that no less than 50% of the water stations were empty at any given time after 4pm saturday, and told the hotel front desk about it.
Parking:
I heard about the power tripping security officer at the empty (as in building for lease)office building threatening to tow anyone who parked there... Some conventions offer a shuttle service for attendees. There has got to be somewhere within a couple miles that has a large parking lot, and is willing to lease it out. Some conventions have their staff park off site, and have a few reserved parking spaces for shuttle staff... volunteers or staff who just drive people to/from cars, go get stuff as needed etc.