If you're into your beer, take a trip out to the Pilsner Urquell brewery. You can get a guided tour of the brewery and sample all their beers at different stages. You can then grab a really nice lunch in their kitchens. Well worth it, when you've finished doing the City. I did this back in 2002.
http://www.prazdrojvisit.cz/en/prohlidka-pilsner-urquell-pro-verejnost/ about 8 years ago