Yes, I agree. Tours! But with a month and a half to go, you'd think there would've already been talk about such things, I guess they think the Wii ambassador parties are enough (I personally don't think so). EDIT: Duh, forgot about the Fusion Tour. But is that really going to reach a lot of people? Store demoes are still more likely to get the casual gamers that Nintendo now wants.
I wouldn't mind handing over a credit card and/or driver's license as collateral (or so that they know who you are if you decide to steal one, since many people have credit cards they never use). A younger person may be less likely to have either of those, but they're likely to be with someone who would. Asking an older sibling or parent for such collateral would get that older person interested in seeing what the fuss is about and then they'd want to try it too. It's not the collateral that's a problem, it's that thefts will likely still occur and moreso the lack of demo kiosks in general.
If the Wii becomes as popular as it is hoped to be, after launch, stores will set up space for a Wii, even if it's not an official demo kiosk unit. They'll figure something out. Like maybe removing the GameCube section for it, like it or not.