I love Aniston - not quite sure why, but ever since I saw her wonderful performance in THE GOOD GIRL, I've loved her.
The prospect of her doing a musical is exciting - although I would prefer her to perform live on Broadway, rather than in a movie musical - which I assume is what she's aiming for.
As said above (and although it's not a musical), Aniston would have been brilliant in THREE DAYS OF RAIN.
As far as musicals, I'm not sure what I can see her in, as I've never heard her voice before - but assuming it's atleast passable (as Kidman's is), it might be fun to see her do a role in URINETOWN, THE APPLE TREE, Smitty in HOW TO SUCCEED, or even SWEET CHARITY.
"If you are going to do something, do it well. And leave something witchy."
-Charlie Manson