We have a big one here (Great Homeschool Conventions) - this weekend actually. I want to see Dr. Carson, but I'm not paying $45 when there isn't a single other speaker I care to see, and the vending hall has almost nothing for me (it's almost entirely protestant, with a few secular options running around - but nothing Catholic and not many secular options). ALL of the science options in the vending hall are young earth. Most of the speakers seem to be parenting, worldview, etc, with less focus on academics.
There is a Catholic homeschool convention a couple hours away, but it's dominated by one Catholic homeschool academy (Seton), and I'd really like to see all of the Catholic vendors represented a bit more.
I base my decisions largely on the vending hall - if I don't like what I see on that list, it isn't worth my time. I have no desire to sit through most of the speakers. My parish priest is, however, speaking at the local Catholic one in May, so maybe... lol.
I would love to go to one, but there has always been a scheduling conflict :/ Also, the majority are very religious around by me. If there aren't a variety of vendors, I most likely won't go unless there are a few topics from the speakers that I want to hear about. The one that's at the end of the month by me for instance, there isn't a single vendor I am interested in, but there were a few speaking events I wanted to go to (I just wish that they all weren't religious based...I was going to put my partial earmuffs on). Turns out I've got a 5K that day at the same time, so o well...
Generally I hate listening to most speakers. I'm not religious and most homeschoolers and homeschooling speakers are. I hate being lectures or preached at. But I have been to one. I paid just to go through the curriculum hall. I didn't not sit through any speeches or lectures. I did find some really good materials I was happy to see, touch and later, buy.