I'd prefer that the J.J. Trekverse stay away from big name actors or actresses unless one or more of the following conditions are met:
1. The star(s) are at least casual fans and they're doing it for the love of Star Trek and not just for the money.
2. If their presence in the movie is limited to a cameo, keep it fluid and subtle, as Praetor suggested. Their appearance should flow easily with the pace of the movie and the storyline, and not be the biggest "wow" moment of the movie. We don't need to hear a familiar voice, have the main characters turn around, and the camera does a close-up on the actor/actress as the viewers say "OMG, they got (fill in big-name star here)!!!" One could argue that Leonard Nimoy's appearance in Star Trek was like this, but his appearance was not a cameo.
3. If their presence in the movie is meant to be greater than a cameo, make sure the choice of the "big-name star" reflects their talent and what strengths they can bring to the story, not their ability to bring in more money here or overseas. Sure, better overseas returns are nice, but not if it means putting in a star that just doesn't fit in the movie's environment.
4. Their appearance must not be overhyped in the media, nor should their role in the movie be too campy or "hambone". The former will steal the focus from where it belongs: the actors portraying the Enterprise crew, while the latter will damage the storytelling and have a more negative than positive effect on the film.