What is the best marathon (1/2 marathon) to run anywhere in Colorado?

I'm 14, and have always loved running, I know I could be great at running a 1/2 marathon, and would love any input from anyone who knows a great one to run in Colorado? Also, I found a great training plan, but if anyone has any recommendations that would be great!|||Depends on what you mean by "best." Some people prefer smaller events vs. larger ones. Some people prefer things on trails vs. roads. Some don't mind hills while some prefer things as flat as possible, etc.