Which Marathon Should I Run?

I have been planning on running the Moab marathon on April 15 but the Colfax marathon on May 20 may be a better option. Colfax is five weeks later and a lot more convenient. Negatives are I won't be able to run the Bolder Boulder, Colfax Ave is not pretty, May 20 could be hot and I will be 59 years old. I've just decided I will only run Colfax if I can't get in Moab. I'll do the Colfax next year when I'm 60.