My absolute favorite mexican food restaurant of all times is Dos Taquitos in North Raleigh. It's a lot more expensive than your typical joints, but the food is to die for. I am especially fond of the steak tacos, and hubby likes the Enchiladas del pueblo.
The decor is something you HAVE to see. When you go in and ask for a table, if there is a wait, you will be given a toy. Possibly a doll, truck, snake, or even a monster. There is an outdoor patio with a folk-art-garbage type fountain, and the decor is shabby chic. Inside there are little huts and the decor is changed very often. it's fun to go and see what has been changed since the last time you went.