I've heard the distant-galaxy idea thrown around a lot but I think that I like this one the best. It keeps to the "Boldy Going" spirit of Star Trek but also emphasizes the thirst for knowledge and understanding of the universe around us.
The only even minor quibble that I have is that if I was on-board one of those three ships I'd be dying to let my people/The Federation know about what we'd discover. Once they go out of range, though, that becomes obvious. I know that's the fate of certain satelites but since they're not sentient beings they don't have to deal with the dilema of learning things, but not being able to report them. (V'ger just wanted to meet it's creators, it didn't really feel the need to tell us about all the space it mapped out.) It would sort of become an indulgance. But now that I think aobut it I guess that has a lot of dramatic/creative potential to it, too.
You get a gold star.