at a glance, paint the bookshelves a nice white such as cloud white(BM) . Take down the mirror and get rid of the curtains. I think a great larger painting in the area where the mirror is would be nice.

whitewash the brick as well

are you keeping the flooring? Hardwood would be lovely

With the look you are going for, the first step in my opinion would be to white wash the brick.I agree with catbella the bookshelves should be painted white as well. I also might consider painting the wood trim a gloss white, and staining the ceiling beams a dark wood.If you get new hardwoods I think they should be just as dark as the beams.

yes darker beams. I agree

I think the reason why your room looks so dark is that the fireplace is so heavy. Anything you do to lighten it will just make the fireplace stand out. Instead I would try painting the ceilings in a dark colour and then making the light work at eye level....
(this is just to illustrate the point)

These rooms mimic yours in some ways submitted for inspiration

with painted woodwork.

I don't know if you have enough room on either side of the french doors/ windows. But, if/when you put up new drapes, make sure to extend the rod out about a foot so that the curtains do not cover up the windows at all when they are opened. Right now the drapes seem to be encroaching on the windows and eating up valuable light.
If you're going to do window treatments again, definitely go with no valence. It just makes the windows/doors feel short and heavy.

Overall, I love the first pic posted by Barnhart. I also like ann dee's pics with no window treatments.

yes perhaps no window treatments

I would leave the brick, door frames, and beams alone. Then, I'd paint the bookcases/mantel a "linen white" or
swiss coffee" type white. The walls a "white". Sort of a White on White effect. Swiss coffee walls and white trim. After you do that, then you can determine if you want to paint the wainscotting white, or leave natural.

Is no one else seeing the gold/brass fireplace? I'd say that's the first finish to change and see how it feels. change it to j

...sorry.
Change it to a black finish.

Yep Hockey...that's a for sure change from the brass.

I agree with white on the bookcases and mantle. Also, get rid of the brass fireplace doors and switch to a wrought iron look. And definitely ditch the drapes. Cream would be nice.

I would use paint to reverse engineer the light = the triangle windows on either side of the brick overmantel really add to the drama of this architecture. You have all wood trim and wainscot and so I would use something rich and creamy to maintain the feeling of richness - ben moore has cake batter - this should be in glossy finish. Paint the bookcases, the wainscot, the trim around the doors. I suggest you paint the brick though these colors are designed to work with it, but test the ben moore color to unify it all - bm cedar key. This will offer a rich looking neutral that will go with many things.

Finally, leave the upper beams in wood tone as they are, but add reverse color by painting the walls this pale taupe - himalayan trek. http://www.benjaminmoore.com/en-us/paint-color/himalayantrek
You can go up only on the vertical and leave the ceiling white. Try a gel stain on the mantle to give it the darker tone to "match" the beams above a bit more. Paint the brass insert on the fireplace (pull out/ paint with high heat oil rubbed bronze spray paint and put it back in).

Change out the fan to a large scale fixture - the ring with imitation candles is a good option. Keep or make an offer on this scale / size of the mirror - if it is yours, raise it from where it is about 18 inches.

1.. LOVE, Love this room
2. paint bookshelves, mantle, and wainscotting white...I'd even debate painting the frame of your mirror white.
3. wallpaper behind bookshelves
4. I'd see if you can intentional aim the upper lighting at your fireplace...see how dark it is up at the top
5. lose gold fireplace, replace with simlar in place and/or decortive iron cover
unsure on window treatments...I personally believe every room needs something for privacy, but can't invision how to make look good.