Diner Dash

You control Flo the waitress, trying to keep all the customers happy from seating them and taking their orders to giving them their food (and bills), then clearing their tables afterwards.

And, though it rapidly gets complicated, the straightforward concept and intuitive interface both help to keep things ticking over a lot more smoothly than the (arguably quite similar) Jazz Night.

Mouse click to where you want waitress to go (or to drag new customers to their tables).

You get bonuses for seating (say) red or blue customers on red or blue chairs (whatever that's supposed to represent), but it's not compulsory - and don't forget you can clear (as many as two) tables in the same visit when you present them with their bill.