My experience is that Piece can get even more crowded than the Map Room other than perhaps on International Night (Tuesdays) and certain Beer School nights.
Chris, the new brewer at Rock Bottom - Chicago, is making some excellent beers. I was in last week and he had a smoked helles and a dark lager that were fantastic.
If visiting 3 Floyds, be sure to also visit Flossmoor Station. It's about 20 minutes away by car. It's also across the tracks from the Flossmoor Metra (regional rail) station so always an easy trip from the City. Other Metra-friendly pubs are: Emmett's (both Downers Grove & Palatine), America's Brewing (Aurora; same line as Downers Grove), and Mickey Finn's (Libertyville),
Other places worth checking out are: Fountainhead and Bad Apple which are both very close to the Half Acre brewery (they have a shop/tasting room). They're bars rather than brewpubs but have good selections.