Eric Zorn blogs on picking sides yesterday and the Trib has a spot for you to vote on boundaries.
I gave my thoughts on the West Sides boundaries in March Bill Baar's West Side: What is the West Side?
Chicago's railroads define the boundaries for me and their spokes radiate far into the burbs. Really as far as you can find someone who appreciates a Vienna Hot Dog and S. Rosen's poppy-seed bun.
Zorn provides some great maps. But Zorn notes one omits the West Side all together.