I have always thought the title was a bit strange, because the Enterprise actually voyages home quote often.
I like the titles of the "Genesis trilogy" taken collectively, because they work quite well as descriptive chapter titles. The first film in the trilogy portrays the wrath of Khan, the second depicts the search for Spock, and the third chronicles the voyage home (by a roundabout route) after those events.
...Undiscovered Country is just a strange title all together.
No more so than any of Trek's Shakespearean titles. TOS gave us "Dagger of the Mind," "The Conscience of the King," "By Any Other Name," "All Our Yesterdays," and maybe "Wink of an Eye," and Shakespeare's works were quoted or alluded to in the bodies of several other episodes. So why shouldn't the movies have continued the tradition? Let's hear it for foisting a bit of literacy on the moviegoing public.
And of course it's a very evocative title to anyone who knows Hamlet's soliloquy (and anyone who doesn't was cheated by their school system), for "the undiscovered country from whose bourn no traveller returns" is death. Which is why Meyer wanted it for the title of TWOK, a film that was very much about the idea of mortality. It's not quite as good a fit for the film it ended up on, though; Meyer kind of had to cheat by giving it a second meaning of "the future," but I guess it was about people fearing the death of their way of life and being afraid to move forward, which does have parallels with what Hamlet was talking about.