In Alberta, there are very few mini-specific shows so most of our options include suitable classes in open horse shows. For me, I look for anything the littles can do - standard is halter and showmanship, costume is a bonus if they have it, driving is very few and far between, although there are driving specific groups that also host events. But to get it all in one, nearly impossible. Nice ribbons are definitely a bonus and people seem to remember that, but I give mine back at the end of the show. Prize money is also really nice, but not always possible with the expenses of running shows. Prizes are always welcome.
Addition of a tack swap or trade show, food truck, vendors of some sort. It's kind of hit or miss if it's worth it for them, but I like to see them and do my best to support when I see them.
For me, the other thing I'm wanting out of a show is to have a lot of fun. I want a friendly environment where I can cheer for my competitors, good feedback from the judge - if applicable, safe location and reasonable price.