Hey wallajwu:
How large is your drive thru? A lot will depend on how much space you have to work with. Keep in mind that space will disappear quickly once you start adding equipment in it. B.T. is right, you want to design your location to address your speed of service. One of the most important elements on the inside is the ease of flow for the operator. Nothing worse than to have a beautiful location, but not operator friendly. You can't imagine how many places I've seen in my time where the owner had no clue how to design the inside and thinking they saved themselves a few hundred buck by not hiring on someone to design it for them. Then found later that they had to spend more money tearing things out and having them resesigned and put back together.
Well in any case good luck...