Searching the Library Catalog with "drama" or "play" as "subject" will lead you to books like:
- Women Writing Plays: Three Decades of the Susan Smith Blackburn Prize
- The Best Plays of 2006-2007
- The Best Plays of 2007-2008
- Best Plays of 2005-2006
- Humana Festival 2004: the Complete Plays
- A Companion to Twentieth-Century American Drama
- The Cambridge Companion to American Modernism
- 24 favorite one act plays
You could try this as a search using the words "theater" and "criticism"
