Casa Grande is my absolute favorite place to eat when I am in Concord. If I could, I would be there multiple nights at week. It is extremely fairly price and the servers are very attentive. Plus, the food is great! I've never been disappointed. I like to stick to my normal of a chicken burrito, cheese dip, and sweet tea, but I know that anything on the menu would satisfy my taste buds.
If you feel up to it, tell them it is your friend's birthday! Your friend might end up with a sombrero, free dessert, and a pie in his face!