This was sort of mentioned, but one thing that helps make a really great test is your uke(s). I say this because they tend to be people whom you know, are probably friends, and whom you don't want to hurt.
I've seen a few tests and the ones that always look great to me are the ones when the tester knows with a certainty that they can preform techniques during their test without worrying about ripping someone's arm off... Well, it makes for a very smooth test.
Now, I'm not talking about uke(s) bailing out of technique, or "giving in" for you. I'm talking about nage preforming strong technique with the foreknowledge that uke can roll with it...
Roll with it! Do you get it!!
and that folks is why I will only do one show a night...