I bought one of those vests based solely on your recommendation, Keeper (I even gave your name when they asked if anyone referred me to them, haha). Definitely impressed with the obscene storage on offer there; honestly I could fit everything I "NEED" to carry with me in one, given that would be "some snacks, a drink, and my money." And plus obviously you have room for ... like, anything else you can think of, basically. When I saw it could hold a 15" laptop I both thought "who in the world would need that?" and "I wish I had not bought a 17" laptop"
ALSO related to this topic, one of the things that has kept me motivated while doing this seemingly endless move I am in the middle of (childhood home was sold at the same time as I was already moving, so I am merging an inordinate amount of stuff together) is making a pile of "things that could possibly be Gen-Con related." Any stickers, pins, or buttons I find go in that pile to add to a bag I will bring; any change goes in a Gen-Container; any clothes that are so nerdy I would be unlikely to wear them anyway before September get washed and packed now; oh, what is in my bag is definitely going to bring me joy for months to come!