I think the room could be much more elegant if you dry walled the end of the pony wall up to the ceiling which would give you a more centered fireplace which could then turn into a focal point with a proper mantel. Right now the set-up looks sort of busy and odd, especially with all the books in the built-in. If you chose to do that I would get rid of the bookcase. If you want to keep the current set up, beefing up the wood on the mantel as Scott Design suggested would be an inexpensive way to improve its appearance. I would also remove the books and put in a few art objects in the bookcase.

I think you're making great progress. CDR wanted you to put them all vertical because she thinks only professionals should style bookcases. We are/were all amateurs at one point, that doesn't mean we shouldn't decorate our own homes. You're getting there! Just keep studying the photos of bookshelves that you like and keep practicing. Just remember to keep the decorations simple. Look over the beautiful photo above from Maureen again, and you can see that some shelves are still all books, and there are only a few decorative pieces.

I understand what you want to do, so here's my suggestion, if it fits.....I'd move the couch under the mirror. Move table to the center of the kitchen, like an island. Sounds like it's two adults and two toddlers, so I'd definitely remove two of those chairs. Are your kids in high-chairs, if so move the other two chairs out too. Basically you want four chairs not six. Move them to a garage, basement or another room. Put the chairs around two or three sides of the table. I'd leave the side near the stove and washing machine(?) open. TV would mount to the right of the back door. See if that would work. Either way, it's going to be a tight space. Post pics please.

Will the radiator be an issue if you want to put TV to left of fireplace? Though it is a more prominent position, you could put the TV over to the right of the fireplace. Back to the window is better as regards glare on the screen if you are watching it during the day time. I would put your sofa in the middle of the room facing the fireplace. then I would put an armchair with its back to the window pointing in towards the sofa. This can be pulled sort of in front of the TV/ forward from the TV which will push the TV into the background and demonstrate that it is not your dominant feature. When you do want to watch TV you can push the armchair over a bit so you can see the TV from the sofa. Alternatively, put the TV with its back to the wall around where the mirror is leaning in your picture. And use houseology's great TV unit on castors idea whichever side you choose! Simple yet genius as you can push the TV right into the corner out of the way when not using - might use that one myself.