I firmly believe there's plenty of sentient lifeforms in the Milky Way, apart from good old homo sapiens of course.
Do I think our planet has been "visited"? Hmm ... hard to say. MAYBE. I tend to think that overcoming the speed of light barrier -- and hence, potentially limitless travel, depending on your speed -- is certainly the first step toward humanity expanding to the stars. But then, it might be unrealistic; we'll have people who feel "entitled" to the inevitable orbital habitat we will build. And then there will be this, and that, and thisthatthing ... *sigh*