Durang will star opposite Marilu Henner in his play this summer at the New Hope Theater.
Guarini will tell stories from his personal book of love in two performances over Valentine's Day weekend.
Tony nominee Sheryl Kaller will direct the upcoming production.
Meet Me in St. Louis: A Live Radio Play will ring in the holiday season at New Hope's Bucks County Playhouse.
Hunter Foster and Justin Guarini are also among the list of the evening's special guest performers.
The five-time Tony-winning actress first appeared on the Bucks County stage over six decades ago.
The Bucks County Playhouse revival runs October 23-November 2.