I have eaten Cascina's prix fixe, pre-theater dinner and it is quite decent. When I went, they even had a coupon on the website for a free glass of wine -- since discontinued. It also has a sister restaurant in Doppo Teatro Doppos, also in the theater district that is good and participates on IDINE. In addition, both are on Opentable, as well.

Am going to see preview of Tale of Two Cities later this month and have selected L'allegria for pre-theater, prix-fixe dining. It is near Cascina, but unrelated, and its prix fixe menu was quite vast. I will see how it goes, as it has gotten mixed reviews on various sources.