This was on Broadway in 1999 - I don't remember a whole lot about the production, except that I thought the acting was uniformly excellent but the play itself didn't make much of an impression. I do recall thinking Natasha Richardson and Anna Friel were excellent as Anna and Alice. Rubert Graves was Dan and Ciaran Hinds was Larry. I also remember the internet chat scene between Dan and Larry to be hilarious and one of the few things I can still remember nine years later.
Car crash sounds vaguely familiar, but I don't really remember specifically.
When I first saw the film I recall thinking it was better written than the stage play (by that time I had completely forgotten the story) but wasn't particularly enamored of it. (I have an irrational distaste for any film with Julia Roberts, so that kind of ruined it for me.) But I'd agree that Clive and Natalie were excellent.
"This is wanting something, this is reaching for it,
This is wishing that a moment would arrive.
This is taking chances, this is almost touching, what the beauty is." --The Light in the Piazza