Well, we never saw Marilyn Cooper (or at least I never did), but I agree that Denny Dillon was great. With Dillon, you noticed Agnes in a way that you usually don't. And speaking of the exit applause for her little scene with Tessie, it didn't hurt that she got to play it with the best Tessie I've ever seen onstage: Mary Louise Wilson, who didn't play cute or put in unnecessary shtick as some later Tessies have. Betty Bruce also didn't do anything like that in the movie, and she's terrific.
Of course, poor Betty Bruce was given several bowdlerized versions of lines. No "troupe of professional virgins" or "Tough titty."