I have a corner fireplace, and the key to successful furniture placement turned out to be turning the sofa on the diagonal, facing directly toward the fireplace, and placing two chairs against the wall to either side of the fireplace. An area rug turned diagonally to the room (parallel to sofa and hearth) pulls it all together. This might work for you. It can be arranged and rearranged in ten minutes. I recommend trying it for a week or two before deciding whether or not it works for your household. A slight variation is to turn the side chairs so their backs are not against the wall behind them, and face directly toward one another, yes with the chair corner to the wall. Of my two chairs, I have one placed each way, and no one seems to notice. If one of the easy chairs is placed diagonally to its wall, it is possible to tuck the television table behind it. The downside of this arrangement: for tv watching, one of you gets the other easy chair, and one of you gets to stretch out on the sofa at full length. (It goes without saying that the kids get the floor). Pattern-with-pattern comes in and out of fashion; one moment it is declared the Next New Thing, and another moment declared an egregious crime. I'd say go with your heart. You want to smile when you come into the room. Congratulations on your new house!

I'd put it on the long wall opposite the window and look into a low-backed u- shaped sectional with the longest side facing the fireplace, the middle part back to the window and facing the TV, and a chaise section next to the fireplace. That's exactly what I have in our house. The chaise section is for stretching out on, and allows everyone to still have the view of the pretty fireplace. We got a custom sofa, for about the same or less than you'd pay at say, Pottery Barn. It's deep and has plush chenille fabric, and it's the best for our rambunctious house full of teens, dogs, and guests. And it seats a lot of people. We also got a big square ottoman that lives at the end of the chaise, but can be pulled over to whereever needed. It's perfect for us. Of course, you'll need to tape off the room to see what will fit. If it won't fit, then please ignore my comment!!!

Doesn't look like you have any wall space for the TV. Do you use the FP?

When the sofa faces the window, the chaise completely blocks the fireplace and looks like a fire hazard. Since you're open to some construction, you may want to consider removing the mantle, adding brick up to the ceiling, then mounting the TV lower than where the mantle is now so it's more comfortable to watch when the sofa is facing the fireplace. If you remove the radiator in the dining table area, will you also be able to remove the 27" and 24" wide wall bump outs on each side? If you can, you'll gain valuable space and may be able to use the table and chairs you have now.