It depends...
New posts on beta hold boards are usually the absolutely first place to check. (Especially on your own boards
) And when there's occasionally something in the Illumination, it's usually worth checking out.
Then, if there's something interesting going, I may check Contests or Architecture. If not, I'll probably go to General, Anything or Electronic Games in no specific order of importance.
By the way, Forum Statistics lists 59 boards in the forum. What does this count besides the public ones? It probably isn't counting everything, because some of the beta boards have id number of 100+. And from what I know, at least some of them are archived after the hold has been released.