Last year I watched my mom run the Salt Lake City Marathon. One thing that was good was that you could watch in one spot, then drive to the next spot. We saw her in several different places along the route, plus at the finish line. The route was lined with cheering people.
This year I ran the Salt Lake City Half-Marathon. It started at the same time as the full marathon. The lines for the porta-potties were horrible. We waited in line for 45 minutes to use the potty. The race course was nice, and there were people out to cheer the runners on. I liked that it ended at the Gateway. I didn't like that there was a water stop missing in the race, so I was very thirsty. I would run it again but bring my own water.