I wonder why no one has mentioned Alice reprising her role. She's no star outisde of Broadway, but if they surround her by more famous people it could work. I'm sure she'd get buzz around Oscar season and could possibly join the legue of people who've won a Tony and Oscar for the same performance.
Diana- Alice Ripley, Toni Collette (though I agree about Tara)
Dan- I'd love to see Patrick Wilson, but George Clooney?
Gabe- Zac Efron
Natalie- options kinda limitless
Dr. Madden/Dr. Fine- Jim Carrey or Neil Patrick Harris for either, or either cut or expand Dr. Fine's role
Henry- Skylar Astin (he's got Hamlet 2 behind his name)
You're reminding me of people you hear at the movies asking questions every ten seconds, "Who is that? Why is that guy walking down the street? Who's that lady coming up to him? Uh-oh, why did that car go by? Why is it so dark in this theater?" - FindingNamo on strummergirl
"If artists were machines, then I'm just a different kind of machine...I'd probably be a toaster. Actually, I'd be a toaster oven because they're more versatile. And I like making grilled cheese" -Regina Spektor
"That's, like, twelve shows! ...Or seven." -Crazy SA Fangirl
"They say that just being relaxed is the most important thing [in acting]. I take that to another level, I think kinda like yawning and...like being partially asleep onstage is also good, but whatever." - Sherie Rene Scott