The Rock n Roll marathon in San Diego was my first marathon.
I've generally spent at least a week every couple months in San Diego since I was very young and then started summering the a few years back.
With all the time I've spent in San Diego, I have NEVER loved the city and seen so much of it, as I did when I ran it. Being able to take in a city on foot, for 26.2 miles is the most amazing experience.
After running that marathon, I did 2 more that year. One in Amsterdam and one in Dublin, Ireland. I was so inspired. If I could run one in every major city in the world I would. As there is no better way to enjoy a city.
Best of luck to you. Make sure that you chug a beer at the Parrot Head booth around mile 21. I grab a been and kept running hard. It actually gave me energy.