Prague is good.
Otherwise for a group of lads I would say Hamburg, Amsterdam or Dusseldorf.
Went for a stag weekend in Dusseldorf 6 months ago. Would highly recommend it. Cologne a few miles down the run is good too
anyone on here know anything about prague? would be good to have some local knowledge.
Lichfield
[MENTION=14574]daveinprague[/MENTION]
London or if you want something a bit cheaper Newcastle.