Driving to a Race--What's Your Limit?

I've been looking at walker-friendly half marathons within driving range of where I live (to save on costs since I'm saving for graduate school), and the New River Half Marathon looks delightful! The only catch is that it's three hours away!  I don't really want to spend the night, but I think I'd enjoy doing this course! What do you think? And what is the longest distance or time you'd drive to participate in a race on that day?

Check out this video of the course: