Reno offers plenty of things to do actually. There is golf of course and plenty of it. But if you are not into golf head out to Sparks(about 5 miles away) to the Wild Waters park. Lots of fun for the family if you have kids and even if you don't.
Here is a quick list of the things I have done or can think of:
Rent a Segway/Take a Segway Tour (Silver Legacy)
Check out the Truckee River walk, it's just south of downtown. Lots of bars, trendy restaurants and art galleries.
Take in a Reno Aces baseball game. About a block east of the Stadium.
National Automobile Museum, on Lake street, just a bit south east of downtown casinos. This used to be the famous Harrah's collection.
Nevada Museum of Art is an interesting couple of hours. It's several blocks south of the downtown casinos on Sierra street.
If you have a car, or are willing to grab a cab, check out Fleischmanns Planetarium @ UNR. It's free except for some of the films and they only cost a few dollars.
There is also Animal Ark, which is about 25 miles north of Reno. It's more of a wildlife sanctuary for rescued animals than a zoo.
Silver Legacy also has a rock climbing wall if you are into that.