Kassab's was a pleasant surprise when my friend and I accidentally ventured in there two years ago.
This is a great laid back restaurant because 1) I have never once had to wait for a table 2) everything on the menu is relatively inexpensive, I have never paid more than $15 including a starter and a meal, and 3) it is BYOB so it is perfect for a small get together with your friends because you will not have to worry about disturbing a crowded restaurant. Additionally there is not a corking fee, at least there was not as of last summer.
I recommend the tabbouleh or tomato and mozzarella (actually its so big it could be a meal) for a starter, and the grape leaves are great as well.