I know Cosby himself is a probably a decent role model as a father figure, but I never saw his sitcom so can't comment on it's content.
Someone recently in another thread gave a list of shows that portrayed single fathers in good light. Many of them were long outdated (e.g., Family Affair, Courtship of Eddie's Father) - that is they appeared before (or just on the front-end) of the feminist foray that sent the perception of a father in a completely different direction. Another on the list was "Two-and-a-half Men", but even on that show the single father is seen as a bumbling idiot with absolutely no backbone (of course it's a comedy, so what'd ya expect?).
Of course when it comes to women, shows like "Ugly Betty" are a hit. She's single (as is her sister on the show, who - interestingly - is a SINGLE mother of an obviously gay SON [wink,wink]), always in control, always bails out the male president of the company, and is ... well ... ugly (meaning, she is strong without the need for beauty to help her out). And let's not even get into the other characters of the show (the _gay_ MALE office worker [wink,wing again], the _power-hungry_ WOMAN, etc).