Richard Greenberg's Three Days of Rain, now on Broadway, is two plays. Act 1 in 1995 shows us the consequences of events in the early lives of three people, and Act 2 is 1960 and gives us the parents of the characters in Act 1. That's where we understand the references and what the title means.
The three good looking performers, Paul Rudd, Julia Roberts and Bradley Cooper, play all the roles, and each actor has two wildly different characters to perform. In Act 1, Rudd is tormented, depressed, a tiny bit over the top. In Act 2, he's gentle, empathetic, and real. Roberts is a stiff sister to Rudd in Act 1, but in Act 2 she opens up and lets it all out, filling the stage with her star presence. Cooper is broad and a bit flamboyant in Act 1 (complete with a magnificent tirade), and uptight in Act 2. The totality works, although I liked the answers towards the end better than the questions implied in the first play, which has an awful lot of exposition, lots of it directly to the audience (not my favorite form).
Director Joe Mantello stages both acts well and keeps the energy up. It's a smart play about seeds planted and the fruit borne a generation later - we taste the fruit, and then witness the planting. Basically a good theatrical evening.