Technically just over the line in Phoenix's Papago Park, the Desert Botanical Garden is the best single introduction to Sonoran desert ecology you can get without putting on hiking boots. Five trail loops walk you through cactus, agaves, wildflowers, and species from desert biomes worldwide. Saguaros 30 feet tall stand directly over the path.
The garden runs a vivid spring wildflower show, a Dia de los Muertos celebration in early November, and the long-running winter Las Noches de las Luminarias when 8,000 hand-lit paper-bag lanterns light up the paths. Allow two or three hours. The morning is cooler and the wildlife — gambel's quail, jackrabbits, lizards — more active.