As there was a conference going on (messe), the hotels in Cologne were all booked.
The only thing I could find under 150 Euros was this HI express in Troisdorf.
A 25 minute S-bahn ride (S12/13), and then another 10 minute walk.
Same HI Express as the others I've been to. Good and free breakfast!
There's not much else in the area, besides a Chinese restaurant, a SUbway and a McDonalds.