I’ve had a lot of cool experiences meeting people in the sci-fi/fantasy world by working tables at sci-fi cons due to two different reasons about ten years apart, but that era of my life is over. I can only go as a regular conventioneer now. I take my daughter to them on occasion if one is nearby because she likes to look at all the cosplay.
I also got to see Gwar and The Misfits do a free double-act concert late at night at DragonCon in the 90s, which topped most of the notable people I met, even though my experience with pretty much all of them was good.