The Truckee River is one of the most beautiful places in California and Nevada. Combine the easy access with some great things to hang out and do makes this a favorite of mine.
There are tons of shops and restaurants, and at times you can find some good food trucks set up on the west end of the park. I've yet to hit up the vinyl shop near the movie theater, but it's on my list. And once the weather looks good, I may force my young kids to hop in an inner tube and take a long float. Ideally, none of them drown.
And if you want to see some really great, old school signage, head north towards downtown.