It would almost be easier to say what I don't use Logic for. I wear a lot of hats, and the biggest thing I love about it is the flexible workflow. I have templates based on what the job is for and screensets specific to the job.
Mixing. I've been bringing Stems from Pro Tools into Logic. The last project I mixed in PT was such a drag, there were too many things I missed about Logics workflow. Plus many of the AU plug-ins were not available as RTAS. And something is wrong with PTs PDC. It's off on several of the busses. Anyway...
Mastering. - I have a great workflow for the mastering jobs, including using the I/O plug-in. I also use the Euphonix, er AVID artist mixer and it helps keep things moving along really well.
Sound Design. - I've done SD jobs for commercials, and also created Sound FX used in a lot of movie trailers. I use Logic for all my editing and Sound Design.
Writing - I don't make a living writing music. Mostly I mix and master, but I have been writing music forever, and obviously Logic is geared for that! Several of the composers I mix for all use Logic. Some of them I've switched from composing in Pro Tools and they adapted much easier then they expected to, and now of course they are much happier.
What I don't use Logic for? SRC, and Restoration. - for that I use Izotope RX2, or Audiofile Engineering Sample Manager which utilizes the same Izotope math.