If you're looking for a great hike for the whole gang (including the four-legged members), the 1.6-mile Wind Cave Trail is a keeper. (Keep in mind that this place is REALLY popular -- the "crowded" factor is why I gave it four stars instead of five. If you crave solitude, your best bet is to go early on a week day.)
The lower half is easy enough for just about anyone -- from toddlers to my 70s+ parents. And although the upper half can be a bit more of a challenge as it gets steeper, I've witnessed many munchkins make it to the top. The trail takes you through some incredible Sonoran desert (wildflowers are a must in March).
Destination: The "cave" is really just a hollow spot in the base of a cliff formed by the wind. Although it's only about 12 feet high, it's shady and provides a great place to have lunch with the local chipmunks (but please don't feed them) and take in the fabulous views -- including (if it's clear enough) downtown Phoenix, nearly 30 miles away.
If you're up to it, to the right of the cave is a much more difficult trail that leads nearly 1/2 mile to the summit. Note o' caution -- the trail is narrow and steep, and includes a rock wall about 8 feet high. But the views are spectacular and worth the extra effort.
Timing: The round-trip hike to the cave takes about an hour and a half (for average adult hikers; allow more time for little ones). Add another 45 minutes for the trip to the summit and back.
Directions: From central Phoenix, I-10 east to US 60 east. Exit Ellsworth Road north to the Usery Mountain Regional Park entrance. Trails are open sunrise to sunset. Admission is $6 per carload.