Since the OP is from Chicago, I second the notion of Metropolis, specifically the La Cordillera blend. From Intelligentsia I only reliably enjoy the house blend, which can be had for $11 or less for a 12oz bag at Mariano's (metropolis cost is about the same). I've had many Intellgentsia varieties but aside from the House, I think Tres Santos was my favorite (I can't remember if that was Costa Rican or El Salvadorian).
There are also an abundance of smaller roasters like Dark Matter, BowTruss, Ipsento, and Gaslight. I'm not sure if Buzz roasts their own, but great coffee and espresso to be had there. I also should not leave out La Colombe (which was mentioned), I've had great coffee from there. Of those I've only brewed Gaslight at home, though I was just given some Bowtruss and when I modify the ratios I have high hopes because their storefront cup is excellent.
It all really depends what you like out of your coffee. I like light roasts because they have more caffeine and the fruity flavors appeal. Those citing Yirgacheffe are speaking my language--always good. And a Sidamo can be quite nice as well.
To the poster that mentioned Panera, I love their espresso roast for making cold press (I just let mine sit in a French Press for 12 hours).
Lastly, Tim Horton's is the Dunkin Donuts of Canada, not the Starbucks.