Some friends and I bought a LivingSocial deal for the Vegas Valley Food Tours. It was super easy to redeem online. We went on the tour on a Saturday at 10am. The guides were friendly and knowledgable about the food and Las Vegas history. In addition to giving us background on the participating restaurants, they also talked to us about many of the places we passed along the way.
I would suggest that people come hungry, or only eat a very light snack before-hand. They work with some great local and family-owned companies that gave us generous samples. Everything was delicious and I definitely plan on returning to the participating restaurants!