After reading your post, I ordered from Amazon and have just received my copy.
[ ... ] I decided to buy "Prefaces to Shakespeare" by Tony Tanner. Written originally for an Everyman's Library edition of the collected plays, published as seven volumes, the prefaces are for the general reader (whoever he or she may be) but by no means simplified in any way other than the lack of scholarly aparatus such as footnotes.
I turned right away to Romeo and Juliet. (A couple of weeks ago we saw an excellent touring production by the Acting Company.) It's amazing reading -- much the most insightful and original treatment of the play I've read. His discussion of the elements of "comedy" and -- to a much lesser extent -- "tragedy" in R&J was an eye opener. It occurred to me that the director of the production I saw might easily have read Tanner's Preface before setting the play.
Tanner discusses the similarities in theme and subject matter in this play and Midsummer Night's Dream, suggesting that Shakespeare may have been working on both plays at the same time. It's no coincidence that each of these plays has provided the characters and story for very effective and much-loved ballets.
2 plays down -- only 35 more to go!