No Obey = Fail pure.
"I might also lend her a Core Grafx, Bomberman and a tap with 5 pads." 
SHe doesn't want to borrow too much though, I've already lent her 3 consoles, but she bought 2 of those for herself. I think she might be getting into it a bit!
A DC is also a good shout. And as of yet, I don't have any fighters in my list...
I've suggested:
N64: Blast Corps
Gamecube: Super Monkey Ball
PS2: Steel Dragon Ex
Xbox: Burnout 3
Master system: Bubble Bobble, Rainbow Islands, NZ story, or Alex Kidd (it's a II)
Out of curiosity, are you going to be there to help babysit your goods? I've ran a few game demo/expos and had issues with kids walking off with peripherals/controllers/games. Not so much as an attempt to steal, but mostly cause they're kids and they think they can just walk off and leave it somewhere else.
Wired controllers Only.
Don't let anyone other than you (Donna?) switch carts/discs.
Have someone display "rules" about treating the consoles/games/controllers.
For OBEY, i've had hits with Kato&Ken and SFII CE. Bomberman is great, but getting 5 people to sit and play for a complete round (best of 3) can be quite rare.