We don't tend to marinate since some of us don't like anything on our meat other than salt and pepper ... rather, we serve it with a sun dried tomato pesto for self drizzling or a reduced balsamic vinegar sauce (from Giada De'Laurentis ... spelling?) and blue cheese.
Sorry, I don't have a specific time that we grill it for, we poke (with our fingers, no thermometers) until the ends are to the desired doneness ... We leave it long and skinny on one end, placing that end over the hotter side of the grill. We leave the fat end on the cool side so it is done rare while the skinny end is well done and the middle tends to be more medium. That way, everyone gets it how they like it. For us, that's the biggest selling point of doing the whole tenderloin - it's multi-functional.