I agree with Stockwell and Jeff.
I think a two day event would be more of a hassle and more expensive more so for the vendors attending than the customers. I don't see how it would affect the customers in a bad way at all, they just pick and choose which day to come or maybe even both. I myself would never be a vendor for two days at a far distant show...maybe once in a blue moon?? But definently not on a regular basis, too many expenses and such. I'm actually more worried with my reptiles being in an uncomfortable deli cup, without food/water than the expenses involved in the two day event.
I think that if shows were held every month that it would most likely get "played out" and boring. Having shows every couple months or even few months, brings in a bigger crowd and is more enjoyable...in my opinion anyways.
*Specializing in Super Hypo Tangerine, Sunglow and Snow leopard geckos!*