There have been a couple of very good threads on here regarding all aspects (good and bad ) about hosting a car show. Check out the search function.
Really depends on what kind of cars dominate your area.If you have a hotrod show and theres only 3 in the area,shows a flop.If you put on a show for all years just be sure to have seperate parking for each division.Theres nothing worse at a car show than walking by a 34 Ford and parked next to it is a Tuner with a wing and lambo doors on it.
On the other hand if you have a good local showing at events an cruise nights. Why pay to go see the same cars you can see free every weekend? I have a friend and their club would put on a killer 3 day weekend show. On Friday evening they would do a cruise night at a local drive-in. When Saturday came for the show at the local fairgrounds, the public wouldn’t show and pay the gate fees. After paying the county for the grounds use it only took a couple years to run that one down.