I want to make sure there are respectful numbers, think the Ava or the main arena would be better?
Not the main arena. You get some players who don't know it is a memorial flight, or who just want to be jerks, and they disrupt the flight. It's happened before.
The Ava arena would be better. It's away from the Main, you don't have side switch issues, and you can evict the jerks.
Please give people at least a couple of days notice. I missed the DR7 memorial because I didn't see the announcement in time. I don't remember Betty, but I might attend to support those who did know her.