I've been jacking around with a post for a few days now. There's no telling how long it will be a-birthin', so in the meantime I'll post some interesting links related to it.
I stumbled across this site about the history of grocery stores. I won't attempt to do it justice - just check it out for a lot of history of the stores across the US.
Are you one of those people who doesn't like WalMart? You might like this from PBS, and get a touch of schadenfreude from deadmalls.com.
Here is some history of department stores.
This has a bit of retail history.