Perhaps you could put a bit more emphasis on the family as well? The teenage daughter only works at night, brings in more young customers, and will some day quit to go to college.
Mom, dad or grandpa could be extra good at cooking (bad stereotype, I just realised), making the mini-games easier.

The daughter could perhaps go to a cooking college, and after a few years, there’s a possibility of her coming back as a full-fledged chef, giving the player a way to make it into a more high class place.

Which of course brings us to decorating the place! You can buy new decor for your place with the money you own, and attract different sort of clientele. Start out as a simple pizza-place, and thirty years later, the place is a fancy, expensive place for the rich people.

Fascinating concept.

There has to be a cleaning mini-game, with the inspector hot on your tail.

You might have to call the police some night; maybe save a neighborhood boy from some bullies. Or maybe some ruthless land developers come to buy you out. Oh, am I sneaking some ‘action game’ into the idea? Might be needed. It cant be all ‘Desperate Housewives’ and Tetris.

I could see doing interviews with real small resturant owners to get actual stories of memorable things that have happened to them, or ways they have grown with their community.

Another gem, patrick. Thanks!