There are so many, but I have to mention the following:
-- A Streetcar Named Desire...particularly with Cate Blanchette, who was an incredible Blanche
-- The Front Page and 'that sonofabitch stole my watch'
-- An Inspector Calls, at least in the last Broadway production. I don't know if it is the play or the production the was so incredible
-- A Moon for the Misbegotten, particularly in the production with Dewhurst and Robards
-- The Plowman...I loved the show and thought the ending could not have been more perfect
-- Nicholas Nickleby...a great ending to a great production
-- Cyrano de Bergerac, particularly in the RSC production with Derek Jacobi, who gave one of the greatest performances I have ever seen
-- Good...IMO, a very underrated play, with a particularly thrilling ending
-- King Charles III
-- The Lady from Dubuque...an incredibly underrated, if flawed play with a very moving ending
-- Long Day's Journey into Night
-- The Great White Hope, with James Earl Jones carrying Jane Alexander's body across the stage. The death was tragic, the pain was intolerable
-- The Prime of Miss Jean Brodie...not a great play, but benefiting from the great performance by Zoe Caldwell. I can still hear 'my girls are the creme de la creme...you give me a girl of an impressionable age and she is mine for life'.