Finding a reasonable French restaurant in Manhattan is hard. Le Rivage fills the bill.
They serve the classics that are hard to find in even France today. They have a great three course pre theater price fixe for $43 from 4- 7 with lots of choices. In fact that is all they offer at that time.
The facility is warm and welcoming with good service and tablecloths. The food is good enough and my wife loved it.
A hint, reservations are a must at that time but if they cannot take you at a table. There is a nice bar and the will serve the price fixe there too.