I think "Will and Grace" was considered successful, and I am told that one of it's main characters is a homosexual, but I don't know for sure, i've never watched a bit of it.
"Are you being served" was a British sitcom (from the 1970s) that lightly touched on the subject and featured a prominent character who was portrayed as probably homosexual. It was an ongoing bit of humor for them to speculate whether "Mr Humphries" was really "gay" or just effeminate.
My favorite,by far,was Mr Mash, followed by Miss Brahams (particularly in the earlier episodes) and Mr Granger.