h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

While visiting the brewery has value as a pilgrimage to the home of the finest beverage in all the world, the hop house is just one large Guinness Co. advertisement (which you have to pay admission for). The only thing worthwhile in the actual place is the two half (!!!) pints you get at the end, which you must quaff with hundreds of other media saturated sheep. At least the Budweiser brewery in St. Louis (although not in the same league as Guinness beer-wise) is free and they take you through the actual buildings.

Although I've not been to the Guinness Brewery, or the Budweiser brewery, I have been to the Bass Museum Of Brewing in Burton Upon Trent. Only a small part of the brewery has been turned into a museum, showing all things to do with the history of Bass brewers and brewing. I do think it's rather good with several buildings housing different things, including a stables, engine room (with working steam engine), vehicle garage, brewery (they still brew beer the old way on a small scale) and a train. The train is the last of the Bass railway, which ran throughout Burton between all the Bass buildings (one of the exhibits is a model showing the railway and buildings of Burton).
You only get one free half in the bar, but they do have stuff from the museum brewery as well as standard bass output.

Its not as bad as all that.
In addition to the history of Guinness advertising (interesting in itself, as the Gilroy drawn adverts are arguably the most successful and recognisable adverts yet) there is a video demonstration of a cooper at work and an AV on the history of the company itself.
Also, the brewery itself would be fairly dull - the whole process is automated and takes place in sealed stainless steel pipes and containers...and this might detract from the "olde Oirish" image they are promoting .