I largely agree with you, although I liked Rinabeth Apostol's Rita a bit more than you did. She plays the role less "tough" than Barrett Doss, but ultimately she won me over. I thought her scenes with Phil at the end were very sweet. Agreed that both Ryan Drummond as Phil and Dean Linnard as Ned were excellent.
Fun story about coming into a show with no expectations: I saw the Broadway production with a friend who had no familiarity with the movie. (I thought she had, until I realized she was confusing Groundhog Day with Caddyshack!) She was put off by the first act (and to be fair, Phil is arguably even more of a jerk in this version), but ultimately she was really moved by the themes of redemption.