Summerhays is probably best known for her stage work. She first appeared as a member of the ensemble in the national tour of
Roundabout Theatre. In 1985, she played Jane and was the understudy for Ann in the national company tour of Sugar Babies. In 1986, Summerhays starred as Lady Jaqueline Carstone in the original Broadway production and Me and My Girl for which she received a Drama Desk Award and a Tony Award nomination. She remained with the production for three years. Over the next two decades Summerhays appeared in several more Broadway productions including the roles of Diana in Lend Me a Tenor, Elizabeth in Taking Steps, Cynthia in The Real Inspector Hound, the musical review Dream, Fritzie and Fraulein Kost in Cabaret, and Miss Madelaine True in The Wild Party. Summerhays also appeared in several Off-Broadway and regional theater productions including Sympathy Jones, Camila,[2]Broadway Gypsies, Good News, and Promises, Promises.[3]