There was no Wikia Game of Thrones panel at NYCC 2015 this year. I happen to live in the New York City area so I didn't need to pay for transportation, but even so, on my own I could only afford a Saturday one-day pass. This meant I missed the other Thrones events entirely, including the main panel. I also missed meeting David J. Peterson or seeing his language panels.
Nonetheless I was able to meet Finn Jones (Loras Tyrell) and Keisha Castle-Hughes (Obara Sand) at the autograph section. I came at a slow point and there was no line, so I was able to talk with both of them for a combined 20 minutes (they were seated next to each other). I said, "Hi, I'm one of the Administrators from Game of Thrones Wiki" and they happily agreed to do some Q&A with me.
They were very nice, though we didn't gain much info we didn't know before -- I mean, as I suspected, they honestly don't know some things only the writers know, i.e. "do the other Tyrell brothers exist?" (probably not, he said), or "if Ellaria is now Tyene's mother, but still mother of "four" Sand Snakes, which are her daughters?" (they never told her) etc. -- but I was understanding about that, I brought it up but at the same time said "the writers didn't tell you that, right?" etc.
So it worked out pretty well.