I don't know what dates you are looking at yet, but I went on
www.hotels.com and plugged in some arbitrary June dates in Chandler... got a lot of hits that look pretty reasonable, in motels that are in the southwest part of Chandler so they are close to the freeway to go down to Casa Grande if you want, and it's an easy drive to go look around Gilbert. Those locations are also convenient to the airport.
Gilbert really doesn't have any motels... I did the same thing for Gilbert, and got mostly hits in Mesa.