What do you mean by availability? There are going to be like 4 million Wiis released in the US. Surly there's a Best Buy or Circuit City or even a Wal-Mart in your town.
Sounds more like you just want a 360, so if you feel that way, go for it. 360's getting a lot of good games this winter and many of the bugs have been worked out of the system. If I had enough, I'd already have a 360, although I would make sure to have a Wii first. I mean come one, Zelda: Twilight Princess just looks spectacular and Red Steel will probably be good for multiplay.