We went last year, was class.
Leverkusen? You stop in Koln?
Going over for the xmas markets.
We stopped in Düsseldorf as it was my best mates stag do, but we went to Koln for a beer festival. Germany is class.
If you can, I'd get tickets in the 'loud' bit at Leverkusen...with the Ultras.
http://www.bayer04.de/bilder/pdf/Preisgrafik_DK_1415_neu.pdf
SD section is where they all are.
There's a supporters bar next to the McDonald's outside the ground. Train station is around a 15-20 minute walk away, but just get some walking beers en-route. Everyone drinks in the street too.
The people are fantastic and I have a proper love for German Football now because of it.