I would definitely seal it and if you know a wood worker have them make you a curved wood mantle. Something with wood against the brick, I think, will make it sing.

Tough decision, since your brick is very pretty. You could white wash the brick; this would simply lighten it up a bit. Painting it is a nice option and will make the fireplace feel more updated. Definitely consider having a carpenter make you a wood mantel that is curved. Love the light wood used on mantel in first picture. Second picture is a pic of brick that has been white-washed and last picture is a picture of a curved mantel....

Other options: keep brick as it is and maybe paint walls in both rooms a color that has more contrast. Here are some pictures that may help.

Great space...beautiful floors. Good luck

I would whitewash both side panels to emphasize the middle radius area and hearth. I'd install two shelves made of reclaimed wood on either side for books or art. A brick enhancer would then go on the middle radius and hearth section.

Clean it good to bring it back to life, and have a nice rounded mantle made as ideaplace222 suggested. You can find videos on how to clean brick on youtube.