I am excluding animated films here, as so many of them are musicals. Also, the Muppets. Also, for those who know me, a note on Rent. Ah, Rent. I suppose my expectations were always going to be too high for it, but I do think Chris Columbus made a number of mistakes adapting Rent for the screen. I could launch into an entire essay, but for now I'll say that the filmed version of the final cast, while not being my favorite troop, is still better than the movie version.
Honorable mentions: Hedwig and the Angry Inch, Velvet Goldmine, Priscilla Queen of the Desert, Grease, Pirates of Penzance, Oklahoma, Camelot, Across the Universe, and the Blues Brothers, which I haven't seen since I was very young and don't remember a lot of.
[Haven't seen: Gypsy, Carousel, The Band Wagon, Show Boat ('36), Annie Get Your Gun, Hustle & Flow, Gigi, The Merry Widow, Damn Yankees, Yankee Doodle Dandy, South Pacific, Paint Your Wagon, Sweet Charity, Ziegfield Follies, the Great Ziegfeld, Best Little Whorehouse in Texas, Pal Joey, Gentlemen Prefer Blondes, Sister Act, Stormy Weather, Cabin in the Sky, Saturday Night Fever, Guys & Dolls, New York New York, State Fair, Kismet, Easter Parade, Cry Baby, Victor Victoria, Alexander's Ragtime Band, Purple Rain, Jesus Christ Superstar, Repo! The Genetic Opera, Dick Tracy, Dancer in the Dark, Thoroughly Modern Millie, Seven Brides for Seven Brothers, The Saddest Music in the World, All that Jazz, How to Succeed in Business without Really Trying, The Rose, Coal Miner's Daughter (I never think of singer biopics as musicals, but...). And I've actually only ever seen bits from the film of Godspell. I honestly can't remember if I've seen all of 42nd street, or just parts. Any of the "Road to" movies. Hey, did you know there's a musical called Hello, Frisco, Hello? I'll have to check it out.]