1. Double Elimination would be the way to go.
2. Some type of handicapping in the qualifying round (Based on high score to date?)
3. Set times that people MUST play at so we can advertise the streams as well as put on the schedule for the event as well. Basically everyone is required to play from 4pm - 8pm Fri-/Sat vs this "play when i feel like it". IF you dont show up you forfeit half of any prize money you would be offered.
4. Have a dedicated meet/greet space along with times to get autographs and talk to players. Attendance is mandatory. Best to do when they open on Saturday - Say Saturday 11am - 12:30pm. This way its not just "random" for people to talk to anyone they wish to talk too.
5. Have mini head-to-head contests and winner of those gets a small prize money. Could also advertise them at a specific time say "6pm Friday - Mini rounds." Everyone kills off there lives and gets to the last man after they get an extra man. Person who makes it the furthest wins. I.E. I get to lvl 13-6 everyone else must get there.
6. ADVERTISE - Get it online and at AE4.0 - A complete list of players and what there accomplishments are/etc.
7. Help streaming and dedicating people who will assist commentating. This can even be done within Discord/etc for online commentators.
This is just a small sampling of ideas I have.