I've been an exhibitor at The Vape Summit Vegas 2014, ECC 2014, and will be attending The Vape Summit Houston 2014 in the beginning of next month. It is a very cool experience. You get to go to a place that's all about vaping. If vaping is something you're interested in or passionate about, there isn't really a reason to not go if you can afford to. I went to VaperCon West in Reno for work, but I wasn't exhibiting.
Play your cards right and you could walk away from the convention with a giant bag of freebies. Stickers, e-liquid, mod holders, drip tips, etc. You get to see what new products are coming out. You get to check out other peoples' builds, which you might not hear about unless running into a random person at a convention. Talk to people across the country (sometimes the world) about what vaping is like where they are from, etc.
It's a good experience all around. If you can afford to go to one, I definitely recommend doing so.