We usually spend Spring Break in Arizona - since my family lives there. If you're thinking of going, here are a few posts from the past that might help.
Four Kid-Friendly Hotels in Phoenix and Scottsdale - Picking a hotel the whole family will love is key. Since writing this, I learned that the Fairmont Scottsdale is launching a new kids' program this summer. It will be a year-round National Geographic Exploreres program. They'll introduc a small fee with the program (it's currently free), but should add a lot of value.
Tanque Verde Dude Ranch - if you've always wanted to stay at a dude ranch, and have your kids take horseback riding lessons, check out Tanque Verde. There are other dude ranches in Arizona, including Rancho de los Caballeros, which I wrote about for Shape Magazine. They also have a kids' program.
Tucson Children's Museum - we loved this kids' museum in Tucson.
Arizona Science Center - this downtown science museum is a lot of fun. We go almost every time we visit Phoenix.
Backroads and Byways of Arizona - my friend Jackie Dishner wrote this great book, with lots of daytrips and weekend trips that even native Arizonans will enjoy.*
Jackie's latest venture is a blog with two other Arizona travel writers - it looks good! It's called Travel & Adventure in Arizona.
When visiting any city, it's good to look for deals before you go. Here are two good websites from my Cities on the Cheap friends.
Phoenix on the Cheap
Tucson on the Cheap
Don't forget to wear sunscreen and drink lots of water! Let me know your favorite kid-friendly spots.