This flat and easy, 11-mile route following the sandy-bottomed Rillito is a frequent winner in this category. Sure, the river is dry on top, but it's still a relatively green and shady route. For north-end bike-commuters, it's a kind of an east-west freeway--one with bunnies and lizards always popping out to keep you sharp. The path runs from near Interstate 10 all the way to Craycroft Road, and along the way, it passes several parks, always hugging the parched riverbed, colored here and there with seeping lushness. To the north, the Santa Catalinas tower close by, and birds scatter and dive all around. It almost helps you forget you're about to pass out from the heat.

Runners up:

2. Fantasy Island

3. Saguaro National Park East Cactus Forest Loop Drive, Park Web site