Are you flying into PRG? If you are, are you planning to spend a day or two there before/after Plzen? Do you enjoy beer?

You can take the train from Plzen to České Budějovice or Brno and spend a day in either town. Both are nice, but I'm partial to České Budějovice. You can tour Budvar there, and it's a cute little town. I enjoyed just wandering around the town for a while. Brno has a technical museum, a cold war bunker, and Špilberk Castle, all of which are open to the public. There's also Karlovy Vary, which is a spa town and is gorgeous. There are thermal springs, a beer spa, and it's the home of Becherovka. When I went to Karlovy Vary, we drove, but I *think* České dráhy has trains that will get you from Plzen to Karlovy Vary.

I don't know if Pilsner Urquell will be open during the festival, but if it will, I recommend the tour there.