Everything I have seen her in has her playing the exact same character: the snob speaking with perfect elocution. I don't know whether that's her real voice or perhaps she's simply great at doing it, but it was the perfect fit for her role on Duet. Unfortunately, as the novelty of the show wore off, so did Alison's appeal as an actress.
Having been part of several short-lived series, she is sometimes considered a sitcom albatross--a female Ted McGinley. It's a label that is probably not fair in her case, given that similar one-dimensional characters have kept sitcoms running for years; Will & Grace's Karen Walker (Megan Mullally) for example.
It sure would be nice to see her more often, but her TV appearances are getting less and less frequent.