When I went to my first Wacken Open Air, in 2002, it was mainly so that I could watch Amon Amarth for the first time.
17 hour bus ride from Stockholm to Wacken, though the festival itself turned out to be more than watching the band once, loved it all and ended up going back for a total of 5 years to WOA.
Of course like so many others traveled to Bochum in the end of 2008 for the Bloodshed eipc saga. Flew from Gothenburg to Düsseldorf and then train to Bochum for the 4 days of shows.
Been to Stockholm a few times, as well as Lund and Malmö, with the only purpose of catching a live show, but there we're only talking a few hours of train rides.
Drove to Örebro from Gothenburg once too to see them, it was further than I had planned, took a while to get there by car
The upcoming US trip will be the most fanatic thing I've done with the sole purpose of watching AA though, but I'm sure it will be awesome