I'm an engineer living and working in Aachen atm. I will mainly go for hashes in the close area which are reachable by train or by bike. Or if I don't forget to check beforehand, when I'm somewhere on the road and I find one one the way.
[edit] Hashpoints I've been to
Köln on Jul 9th, 2011
Liège on Jun 10th, 2011