Often good re-decorating requires taking some elements away, but you are asking for a feel of luxury, so you need to carefully add elements. If you have enough space and budget, then consider continuing the built-in to the other side of the fire place, and painting all of it to match. That will anchor the fireplace as the focal point of the room. Fabric can really add a sense of luxury so you could raise the curtain rods and add longer drapes on either side of the windows, with a filler spanning in between, not a swag, but something like you'll see as an example on the the first picture that Beverly posted. Original art says "luxe" and it looks like you have space for a great and sizable piece of art on the wall adjacent to the sideboard across from the dining room. Larger accessories absolutely, and some that are taller. They don't have to be expensive, but they should be things you really enjoy looking at and that you find delightful, or even amusing. Garage sales and flea market are gold mines. Then look carefully at the 2nd pic from Beverly and you'll get and idea on how to do a collection of smaller items to make a bolder statement (collections are 3 or more items.) The key to unifying is color. You've done a good job with your neutrals, add a couple of more luxurious throws in that palette and a few pillows. It looks like you enjoy blues so add that to the mix as well and a pop of black here and there and you should be well on your way.

I would probably stick with one color for both rooms, if it were me. I instantly thought of BM Grey Owl for what you are describing. It is slightly blue-green while still being a warmish grey. I love it, but it was too blue to pair with my pinkish carpet in my house (didn't want a pastel color combo going on!) I also like SW Passive, but it is a little cooler. If you do the blue kitchen, I would caution against a warm grey with too much pink in it (the baby room effect). I'm definitely no expert, but I just bought my first home too and have spent MONTHS researching grey paint! I ended up selecting SW Useful Grey. It is a greenish grey, which I never thought I'd pick. I guess I'd just suggest taking your time and keeping an open mind when looking at colors :) And definitely buy samples to test in your home...

I love the clean, uncluttered look of your home and you've made some great furniture choices. My first thought, though, is that I would try to rework the sofa/sectional placement. It really is unwelcoming looking to me to have the back where it is facing a wall, when it could be oriented to look into the room and out the windows. It seems like if it were placed in the corner under the stairs that it would feel open and invite you to come in and sit. I'd hate to be cooking in the kitchen and have the family or guests with their backs to me. If you are having a TV in another room close by, do you need one in that room, too? If, so placing a 70" unit will probably only work as you have it. But, to me, it's not going to look like a living room but more like a movie theater, which is fine if that's what you're going for. It seems like it won't be a cozy conversation area, though. I might actually flip the rooms and put the dining room where you have the sofa now. I was looking at lights used with dining rooms and ghost chairs and saw this, maybe would work in the living room? Kind of fun. don't know if it would look as good without the colored walls though. And I thought something like these were interesting to consider for over your table:

I like the RH chairs. What do you think of a light similar to this for your dining table? I would move your art work over the dining table so the frames are about 2" apart. It will have more impact grouped closer together. I very much like the brass shelf in its current location. The wall color is dark and the metal gives a nice contrast. It's also very well arranged. The t.v. console you've chosen is great. I like that the brass ties into the shelf and lamp. I would choose another sofa versus a sectional. Two sofas would work versus a loveseat if you have the room.