Just sayin', as I get better acquainted with the hundreds of beers available in this area, the special limited ones are usually the best, or at least most interesting to try. Not that these are all extreme beers, but they usually cater to the aficionado, which I believe I am. And where do you find these one off offerings? One place is at the brewery's brewpub. The other is at your deep beer bars.
For the former, look to Three Floyds (Munster, IN.), Two Brothers (Warrenville, IL.), or Goose Island (Chicago, IL.). I have been to the first and last, not the middle one. At Three Floyds on a day trip in 2007? we found a delightful cafe environment with many FFF beers on tap, including several you will never find in a bottle. At the Goose Island Clybourn brewpub, brewer Will Turner regularly creates wonderful experimental beers on tap or cask that never make it to a bottle, and rarely repeat.
As for the bars, notable are the Map Room and Hopleaf, since they don't make their own beer, they can get some out of market beers that you will never see in Chicagoland anywhere else, or certainly not at the aligned brewpubs. Examples, Hopleaf currently has on tap the Surly Cynicale, a nice Saison only available in cans (yeah!) that are not distributed in IL, and surprise a FFF Smoked Helles (not even listed on their website or at Beer Advocate), a one-off beer you'll never see in a bottle unfortunately.
We are in this time in history lucky and fortunate to be alive when great brewpubs and beer bars cater to wide style of tastes, so get out there and keep widening the options by supporting these great brewers, the one-offs they produce, and the bars that carry them.