I also like events. As far as I am concerned the most important thing are the people you meet.
I like to host events in places that I visit abroad. Till now those events have allways been a success, as local "event lovers" are comeing by and you learn a lot about the nicest caches arroound. So for me it's definetly both: old caching friends or the new cachers (-:
At my first self organized CITO there was a new publish at the same time. Most of the attending participant found that rather distracting. On the other hand at a "normal" Event - why not?
Food, if not (semi-)obligatory is allways good for talk (-:
try something new? I think it's a draw, although I haven't tried it jet, except for MEGA
easy to get to and accessible for all is my first choice, but sometimes you have a chance to combine beatuy (-:
Size does not matter (-: Even at a well visited GIFF talk was still happening (-: Comination with Souveniers helps most of the time....