A good reference list of plays worth reading is the contents of THE BEST PLASY... series of books. Each season from 1919-1920 until 1994-95 the editors chose the 10 best plays and musicals each season. They included all the major award winners but also some more obscure plays that maybe only had limited runs or off-off-Broadway stagings.
It was through the BEST PLAYS series I first read STICKS AND BONES, THE KILLING OF SISTER GEORGE, THE GREAT WHITE HOPE and many more. Of course if you enjoy their abridged versions you can search out the complete text.
A shame they have done away with running a detailed synopsis of each play in favour of essays about the chosen shows. Still for the statistical data (Cast changes, awards, performances) the entire series is a must for any theatre fan. I have the complete set including three volumes covering the early years (1884-1919) that were added to the series in the 1950s, and I await each new release eagerly.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com