I will not be at CAP Euro, although I hear it is going to be a great conference. I will however be attending CAC in Amsterdam. I think the most important aspect of these is the new relationships you will develop as well as the deals you can secure.
The lectures and sessions are good for the newer people, but often times they are lead by your peers, so essentially you can get just as much of this info researching or reading forums.
Once you have met people face to face and shaken hands, it makes doing business together much easier in the future. And as Brandon mentioned, some of the best business and networking can be done afterhours. Even if you're not a big drinker, plan on at least staying out late.
Another thing I always try to do is be on my "A" game at all times, even if I was out late the night before. It is important to differentiate yourself as a professional and a "player" in the industry when having your first meetings with affiliate managers. This will go a long way for you down the road.
Like Brandon said, it is good to hook up with a few guys from PAW that have been to a few of these so they can introduce you to the AM's and other affiliates.
Have fun, maybe I'll get drunk the night before and book a flight to London.........that's how I ended up in Miami at Spring Break.
For your reading pleasure, here is an older article about
The Importance of Attending Industry Events