For a land-locked state, Arizona has many beaches on lakes and in rivers and reservoirs. http://www.chiff.com/recreation/beaches/US/arizona.htm Tempe Beach Park has a Splash Playground. Lake Powell is a man-made reservoir and has red sand beaches. http://www.powellguide.com/ Several roads in Arizona lead to beaches on the southern shore of Lake Mead. http://www.americansouthwest.net/arizona/lake_mead/nra.html
I've heard Lake Powell is a nice lake. Anyone in Sun City looking to have a day out could certainly make a nice trip going to Lake Powell.