I've tried all kinds of things, from oils to butter to a soak in Italian dressing. In the end, I discovered that I prefer my steak surface to be dry when it hits the fire. I sometimes even salt and pepper my steaks the day before cooking, and let it sit in the fridge to draw moisture out of the surface -- a mini dry age.
I like the nice crust I get on the steak when I grill a steak prepared like that over high heat. A tasty crust on the outside, and juicy medium-rare inside.
If a guest wants their steak done more (even well done), they still get a juicy, flavorful steak.
That's my own personal preference.
CD