Oh, one thing I noticed at signings... Dragoncon seemed to combine signings for one author they expect to be really popular, with an author or two they don't expect to be popular. For example, they had Brandon Sanderson in a room with a big line for him, with 1-2 other authors who had maybe a fan or two. I felt terrible watching that, personally, so I had my husband save our space in line while I met the other authors and found out about their works. I had some interesting conversations, and felt like I was helping newer authors who probably were uncomfortable in that situation, so I'd recommend doing this if you have someone to save your spot.
And if you have a chance to meet Brandon Sanderson sometime, he is *REALLY* nice. I've met him 3x and he was always polite to every fan - even the few who were rather rude to him. And his events aren't as crazy as Jim's so you don't have to be there as early. Plus his writing is awesome.