I'd like to suggest Franks Famous Hot Dogs in San Luis Obispo. They're on Monterey Street, off the 101. It's been there for years, owned by one family forever, and I think was purchased by employees a few years ago. Dogs are great, burgers are made with natural beef, and the fries are amazing. Prices are great, too! They're not the fanciest place in the world, but locals love it, and pack the place every lunch-hour.