I was able to attend this years Steam Developer Days and had a great time. One big draw of the conference was the talks and Valve has dropped them all on their YouTube page. I linked to one really great talk above by Mike Ambinder on the Psychology of Games I recommend you watch. There are 25 talks available from this years Dev Days so if you are in need of some awesome game talks and have some time, hit the link below.

https://www.youtube.com/playlist?list=PLckFgM6dUP2ihiMeKHoyIdHvhRSyqwQsp

If you want to read my thoughts on my two days at Steam Developer Days hit the links below.

http://cheerfulghost.com/jdodson/posts/3127/steam-developer-days-day-1-vr-is-all-around-you
http://cheerfulghost.com/jdodson/posts/3132/steam-developer-days-day-ii-a-wrap-up-to-a-great-conference