Fulham 1 Cardiff 5, my first away game as my rugby loving uncle took me as an early Christmas present. I was so excited about the game that I insisted that we were stood on the end where the away fans go now about ninety minutes before kick off and about a quarter of an hour later, about fifty City fans ran onto the Hammersmith End at the opposite end of the ground and started singing "we have taken over". The few Fulham fans present at the time stayed well clear of the City supporters, but they got braver as more of them entered the ground and there were some mild skirmishes that got my uncle into his best tut tutting "you'd never see that at the rugby" mode.
I was twelve at the time and never asked my uncle to take me to an away match again - I was soon old enough for my parents to let me go away with my mates, but I also figured he'd not enjoyed the experience much. Of course, I thought it was fantastic and, as it turned out, my uncle gave me a shock decades later when he told me he'd really enjoyed the game and was really taken aback by how well City played.
As for favourite away grounds - Highbury, Villa Park, Upton Park (when I went to watch a game as a neutral!) and Goodison Park spring to mind and, at the opposite end of the spectrum, I always found the Manor Ground, Oxford such an odd, but likeable ground.