This is a great bunch of responses - thanks everyone!
My only experience with the two kinds of venues I mentioned above in the first post was when I thought I would sell a ton of Christmas and Halloween "yard art" which I had cut on the CNC and hand painted. That was a waste of time and materials but it was sort of fun the first two attempts. I also tried sandblasted ceramic tiles with various kitchen related graphics and sayings. I still think that idea has some merit - laser engraving the tiles will take the mess out of the job and eliminate the need for sandblast masking. They could be used as hot plates or trivets with rubber pads glued to the bottom of the tile. The drawback is they are heavy and will break if you drop them...
I agree enthusiasm at the shows is very important. From my own experience in seeing vendors that look bored and disgusted because nothing is selling - their attitude makes people want to stay away. A little friendly conversation with people as they approach helps them feel like you're just a regular guy or gal and maybe you have some interesting stuff they might like. There's many ways to sell and that's a whole topic in itself.
Knowing what people will buy is somewhat like gambling in that we have to put up the money and labor and make a stock of items and hope it's a win. I had expected to see mostly negative comments about craft shows being a waste of time because for my experience with them, that's mostly what they were. They were low attendance shows with $1.00 or $2.00 to get in and it seemed like people were there just to support the venue and they had nothing to do that day any way. But it was encouraging to hear that success at the larger shows is still definitely possible for some people.
There's a big pet related show coming up soon that I was considering. I do have a higher priced product for dogs ($75 to $125 depending on size) and I would try to have a bunch of lower cost items as well. They have 10x10 booth space or 10x4 space and last year 10,000 attended. Part of the $6.00 admission fee helps local pet rescues. I may give this one a shot instead of the small shows I tried before.