9. Honolulu Marathon

The Buzz -- There's a lot to be said for a marathon course so beautiful that runners carry cameras to capture the beauty of the landscape. That's the magic of this oceanside route, which begins and ends in Waikiki but climbs to Diamond Head for its most trying leg. The December event usually features temperatures in the low 80s, along with cooling breezes, and the circuit is largely flat. Begun in 1973 with 167 participants, the marathon now attracts more than 28,000 runners annually.