Cleanliness is a big one for me. How clean the facility is and how friendly the barn staff is. Another big thing is the fencing, what type and how well cared for the facility is. I would want to take a look and make sure clean water is something that is readily available to the horses. Arenas-they have to be in clean condition without any manure left behind.
KCJo .. I would nix the outside trainers. I have seen it at large public boarding, and my o my
Does the stuff hit the fans..
You could suggest boarders meet and use your Vet, but always have more than one Vet in case of emergencies, vacations, illness etc.. Vets have problems and family ! And you really don't want anyone bad mouthing your Vet or any Vet in the area. Word does spread that this barn or that barn said such and such..
Feeders.. you can get barrel feeders for the ground so they are not in teh dirt as much, or put down old stall mats and put the hay on those to prevent sand.
I have pipe and tpost with hot wire.. I had board fences, but they did not last long, what they did eat the just pushed through even with hot wire on it. Cannot wait until I have all the pastures in Pipe..