"I might be shot for this, but compared to the original Hal Prince staging (which I think is a snoozer), Evita as a film has many elements that worked on its favor better than it does onstage."
Hal Prince's EVITA a snoozer? Have you actually seen the production as directed by Prince (and not merely restaged by one of his underlings)? I saw the original cast on broadway as well as some replacemnet cast and the first national tour. Always found it crisp and fast moving. So I am not quite sure what your frame of reference is or what you were expecting.
Having said that, I think the film is about the best possible film that could have beeen made of the piece. Some of the changes (like giving "Another Suyitcase" to Eva herself and shifting it earlier) were brillianst. I find the film really beginsto drag near the end and "You must Love Me" is a needless addition.
As for some of the best stage-film transfers I would include FUNNY GIRL which is much improved over its stage edition. CALL ME MADAM is tighter and faster on film.
Mike Nichols film of VIRGINIA WOOLF is excellent. He took a 3 hour play and shortened it by an hour and yet nothing of import is lost. And the film has a cinematic feel. Often plays seem terribly stage bound when turned into films.
Cast albums are NOT "soundtracks."
Live theatre does not use a "soundtrack." If it did, it wouldn't be live theatre!
I host a weekly one-hour radio program featuring cast album selections as well as songs by cabaret, jazz and theatre artists. The program, FRONT ROW CENTRE is heard Sundays 9 to 10 am and also Saturdays from 8 to 9 am (eastern times) on www.proudfm.com