My family and I very much enjoy the Phoenix Zoo. My children are all teenagers. We have maintained a membership for several years now and go 6 to 10 times a year. Zoolights is also one of our favorite holiday evenings. The young ones (and us oldies) also enjoy the splash pad to co off in the summer.
My husband and I plan ti rent one of the bikes soon with a picnic lunch at the lake there.
We also recommend ending your day at Papago Park watching the sun set from Hole-in-the Rock.