I was at Gamescom, but sadly was was in back to back meetings the entire time. Nearly all of my time was spent in the business areas, although I did head through the entertainment area once, and went past the retro area, which looked very cool! I think next year I'll try and end up with a spare morning or afternoon to actually look around a bit more.
In terms of travel, I'm UK based, and for this trip decided to go via train (getting sick of flying, all the waiting around and uptight atmosphere). I quite enjoyed the train journey out, from Chester (between Liverpool and Manchester in the UK) my route was:
Chester -> London [2 hours]
London -> Brussels (Eurostar) [2 hours]
Brussels -> Cologne [1h 45m]
So about 6 hours all told (compare to flying: which is 30 minutes to get to airport, 2 hours at airport before flying, 1h 30m direct flight, 30 minutes at airport in Cologne, 30 minutes to get to town, comes to 5 hours). So the journey was an hour or so longer, but a lot more relaxing/enjoyable.
In terms of accommodation, we stayed in an Ibis which is a 2 minute walk from the Barbarossaplatz overground train stop (which is about 5-10 minutes from the conference centre). For the record, the train system in Cologne is very good, and runs until late. I think next year I would be tempted to get a hotel a little further out (all the nice hotels close to the conference centre sell out very quickly, and the remaining choices are very expensive). I didn't really rate the Ibis we stayed in very highly, but was good enough for what we needed.
I typically find at these conference events there will always be places giving out free food/drinks in the evening, you just need to get an invite for it. So if you were looking for a bargain trip you could probably get by with quite little subsistence money.
I might do a more full write up on my experience at Gamescom this year, but what I will say is it the first time I've been (I typically do GDC and BlackBerry Live/World), and thought it was a good event. I think it is very likely I'll go again next year!
