Have not myself, but know a couple people who have been there. This is what I recall them telling me years ago:

Sun on the salt is super intense so you'll need a good hat, sunscreen, and shades.

Supposedly the cars are raced pretty far from spectator's viewpoint so may want to bring some binoculars?

Longer downtime between runs to clear the lengthy course so don't expect cars to go down at the same rate as what you would see at a dragstrip.

Don't drive a good older car on the salt unless you plan to thoroughly clean every nook and cranny of it later. By later they mean asap.

Don't stray from the designated drive zones. People have been known to do stupid stuff and get stuck in softer parts of it that have moisture under it.