There's nothing I enjoy more than a relaxed day trip on the light rail. I hop on somewhere around Camelback and ride downtown or all the way to Tempe.
The people-watching is fabulous (although, after dark it can get quite sketchy) and keeps me entertained on the somewhat slow ride. Yesterday, for example, a strung-out woman was discussing getting tattoos on her neck to cover up all the scars from where people tried to slit her throat. Disturbing....but certainly makes for an interesting ride. Especially when she yells out to no one, "I DIDN'T NEVER DATE NO F*CKING WOMAN!". Pretty awesome, if I do say so myself.
The light rail is cheap, clean, convenient, and always fun. It is a must-do for any downtown visit. Enjoy!