I’m no expert on the Marine Corps Marathon, but after running it (almost) twice and spectating five times, I have a few insights to offer on getting around, seeing people you want to see and getting them the encouragement they need.
First off, it’s a good idea to sign up for runner tracking. Though it may not always offer instant updates, it’s a good way to keep an eye on where people are at 10k, 20k, 30k, 40k and the finish.