I'm in the Milwaukee area. Aquatics Unlimited is big and probably your best stop for live plants. I've soured a little on them as they have hiked their prices up crazy high the last time I was in. I understand the state of the economy, but it was a little excessive..
Another one worth checking out is Hoffer's Tropic Life Pets. Haven't been there for awhile, but they carry some equipment you won't see at the others, like Hagen's full line of aquariums like the Osaka and Venezia setups. They often ran weekly sales on equipment as well.