The Zoo Story, 'Night Mother, Happy Days, Love Letters, and Oleanna are the "classic" ones that come to mind. In recent years, Constellations, Guards at the Taj, Sex With Strangers, Venus in Fur, Blackbird, The Mountaintop, The Niceties, and Slowgirl have all been very popular at major regional theaters. As for musicals, the ones I can think of are The Last Five Years, John and Jen, Daddy Long Legs, and I Do! I Do!