For this situation, I would say the thinner the better, which is not my normal approach to steak. But with a thin steak sous vide to rare and a raging hot sear/grill, you could color the exterior and warm the center of a thin piece.
You'll overcook a thick steak and/or have a cold center with what you're proposing.
If you can, set them up for the bath so they are finishing just before you leave. Keep them warm on the way over and sear immediately.