Everyone I know seems to want to score a Wii on launch day, and most are betting on second tier outlets to get one. I agree and think that the world will line up at Walmarts, Targets, and BestBuys around the country so the secret is to find another option that is big enough to get Wiis on launch day, but also not so big that anyone would notice. This could be a local mom & pop store, a non-franchise video game store, or that seedy Kmart in the bad part of town.
I tested this theory out by visiting my local Fred Meyer. If you're in the Pacific Northwest and near any major city, chances are you are surrounded by Fred Meyers. I don't think I'll hurt my chances by sharing that they're open from 12:01am-1am this Saturday night and my local one has 75 Wii consoles ready to go. That's a lot of boxes, right up there with what most BestBuy stores will get and about double what any Target store is getting near me.