Went to Gatecrasher in 98 and 99. 98 was at the normal home and the disco biscuits were ace before going back to the hotel and listening to Sasha from the Ally Pally on the wireless.
Millennium eve at Don Valley was just utter shite, overpriced, cold and utterly over hyped.
Only other one I remember was Renaissance in 1996 somewhere in Nottingham with some fluffy clouds bereft of atmosphere.
Stuck to house parties after that.