actually budapest is an excellent place for an event like this.
its cheap, friendly, lots of booze, loads of parties, very good night life, lots of hotels, fabulous roman spas, beautiful at night and during the day, superb public transportation. crime is very low. many times i’ve been pissed beyond belief and still managed to get home without any issues (whether by foot or on my knees).
the only drawback is that weather in september can be different. sometimes it can be around 20, other times around 15. but its not too cold.
i’ve lived there for a very, very long time and its definitely on the recommended list for anyone who has never been there before. and its much funner that prague too 
we can even make a lil puskas footy tourney in the massive stadium with renee as a striker. following her uncle’s roots you know…