Freedom. Not having to clock in, clock out, and just generally keep a schedule. Being able to wear sweat pants instead of pencil skirts. Always having the option of going outside on a nice day (you know-- for research purposes ...).
But if I'm honest, the true freedom comes in being able to reside in worlds where good always triumphs over evil. We sometimes get so caught up in plodding through the "real world" that we can't see the sun rising behind us. But in an author's world, her eyes are omniscient: she sees the dawn coming from over her character's shoulders. She knows that, in just a few moments, everything they've gone through will have all been worth it. The light will cross their feet and they'll see that all the while the sky was dark, they've actually been heading in the right direction.
We don't always turn to see the dawn in life. Most of the time we don't know if we've been heading in the right direction. So it's freeing to be able to travel into worlds where things are simpler.