A trip to Vegas just isn't complete until you roll through the Fremont Street Experience. It's definitely worth the short excursion...just park somewhere down the street for free. If you roll into the El Cortez, hotel parking is free...not sure about the other casinos in the area.
There are casinos here, a strip club, restaurants, souvenir shops and of course the light show. Shows every hour at the top of the hour starting 7pm I think.
It's definitely worth an hour of your life.