Where the Mojave and Colorado Deserts meet, there lies Joshua Tree National Park. We loved the park's flora and fauna--miles of medium-sized cacti as far as the eye can see in one place, then drive a couple of miles and view a Joshua Tree-covered landscape. Enormous rocks and piles of rock give you the impression that you've landed on Mars...until you see the petroglyphs, that is. Lizards and small chipmunk-like animals abound, and in a five hour visit we encountered two coyotes; one seemed unimpressed by us, the other made a beeline for our car, undoubtedly in hopes of getting some grub.
Bring plenty of water, $10 to enter the park (good for 7 days), camping or climbing gear if you're brave, and your SUV if you want to have access to all paths open to visitors.