Coldest - Juventus away in the Europa, December 2010, around -10 C in the stadium then I ended up on the wrong tram after the match and had to walk for half an hour to get back to the hotel by which time I must have been close to hypothermia.
Furthest - without checking distances I'd say Thessaloniki for the Aris away match.
Scariest - Forest in the Cup in 1974 was really bad, kicked off all over the place before, during and after the match. But there were many violent away trips in the 70s, especially before proper segregation was introduced, any trip to Leeds or Merseyside was one where you had to keep your wits about you at all times.
Fullest - the South Stand paddock at Elland Road, Xmas time 1976, never been so crammed in on a terrace before or since. Kiddo scored both goals in a 2-0 win.
Emptiest - Chelsea away on a Monday night in 1993 was weird, just over 10,000 there for a Prem match in such a big stadium, dead atmosphere and a totally uneventful 0-0 draw..
Most enjoyable - I've got to go for the 6-1 at the swamp, just for the sheer pleasure of rubbing their noses in it and the "fire drill" with 20 minutes left.