We use the Stand-N-Stuff kit by Old El Paso, cooking according to the box directions.
But, Alex is a big fan of the double wrap tacos, so we also have flour soft taco tortillas available. He uses one soft taco tortilla, smears refried beans (from a can) on it, then secures the hard taco shell inside it and fills it with beef, rice, sour cream, cheese, salsa, whatever.
It's nice to have the hard and soft shells available, for variety, and it's also great for leftovers. I generally end up making quesadillas the next day--putting the refried beans, or any left over taco beef, and rice and cheese between the tortillas and heating them in a pan. Then I serve them with sour cream, salsa and guacamole on the side.