G-APDK you do a great job within the limitations that you have!
Here is what I would like
Absolutely no slots! I dont like them but more to the point is that lots of the owners of interesting aircraft we want to see dont like them so dont come. People think they are restricted to getting there exactly on time- like was the case at one event, and dont realise that its a bit more flexible!
Grass and hard runway available
Good quality "Air Traffic" air to ground is good enough, as can be seen at Popham and at the Today's pilot fly -in. Tell Air Traffic that they can look at the booking-in/out log afterwards so they dont have to spend all of their time asking pilots for booking in/out details while others cant get a word in on the frequency. It should be minimum radio chatter.
Access for all to the aircraft parks
reasonably priced food/drink- like at Popham in the clubhouse.
All the hangars open for viewing- usually good at your event!
Minimal bureaucracy, no yellow jackets except for Marshallers (or Marshallers wear something else distinctive)
No limitations on flying time ie "artificial airfield closure" Its great to do evening flying and giving rides after the traffic has died down. Even better if "ATC" have gone home!
Thanks.