I go to Droubi's in the Downtown tunnels at least once a month. Their gyros are fabulous. Anytime I go to a Mediterranean restaurant, I only get the gyro sandwich, and Droubi's is the best I have had. For about $5, you get a gyro sandwich AND a salad. It's such a good deal!
The restaurant is pretty big, but there is always a lack of tables. That's how popular this place is. Give it a try...you won't be disappointed.