Yes to an hour or so at the Desert Botanical Garden in Phoenix, but maybe paired with something more action-oriented, like:

• Octane Raceway in Scottsdale
• Horse rides at MacDonald's Ranch in Scottsdale
• Hike up Camelback in Paradise Valley
• Hike in the McDowell Sonoran Preserve in Scottsdale (Gateway Loop)
• Rent bikes and ride the Camelback Greenway in Scottsdale
• Boating rentals on Tempe Town Lake
• Gilbert Riparian Preserve at the Gilbert Water Ranch

Don't forget to have them wear hats. Our winter visitors' kids will get badly sunburned on the tops of their ears out on a horse/bike/kayak/hike without a hat.