What a fun space! Love the pillows...I agree with above, lower all the frames, but not so low little ones can reach. The art should fall at eye level about 5'4" for walls and for behind the sofa not more than 12" above it. Then keep the width about 5" inside the sofa length on each side. Your frames are small so you need the close together for impact. I would start with some pretty curtains for the door and large window and then a simple Roman shade for the small window- since your girls play there you don't want anything they will grab hold of. http://www.houzz.com/ideabooks/query/how-to-hang-a-photo-gallery

There is nothing worse than ceiling-mounted lights--harsh shadows, flat lighting. They are strictly for utility. I would put a large-ish, shallow cylindrical shade on them and put nothing more than a 15-watt bulb in them. Use them strictly for lighting your way as you walk through the room. I agree with Vincent; the chair in the corner doesn't fit at all, nor does the one under the A/C unit (put that one with its mate behind the love seat). And the curtains look smooshed. I think the problem with the bookcases is that they are uninteresting. Did you buy books-by-the-yard? What are all those identical books? They are visually uninteresting. I'd get rid of some of them and get some colorful ceramics/glass/photos. The room is absolutely overwhelmed with furniture. It needs one less love seat. Do you really need all of them? Pushing them against the walls/curtains so tightly just visually emphasizes the fact that there is too much furniture. I don't think a mirror above the fireplace will work. When people are sitting down (which is most of the time), all they will see is a reflection of the ceiling--the plain, white ceiling. Get some real art in there with some color.

Despite previous opinions I have to say this - DON'T GET DOWN LIGHTS!!!! We had them in our previous home. They were constantly blowing no matter what kind of bulb used. The casings kept breaking. This meant we couldn't just change the bulb ourselves. It drove me mental. They spotlight certain parts of a room instead of lighting the whole room so when one of our main "culprits" kept blowing in the kitchen, I had no lighting above that bench until we could get an electrician in. More than one electrician told us they are a serious fire hazard. I will never have them again!

I hope you guys covered the ceiling.