The op already mentioned that they tried using a 2-channel setup (for a phantom center) but the dialogue levels were too low. My first thought was that they really need a capable center. The center channel carries most of the dialogue in video content and will be adjustable with the Cinema 30. Agree about the aesthetics. You get used to those things over time. With the speakers like the 803 for mains, the TV speakers will likely be a very poor option for center channel duty. The op should give serious consideration to a good center. The Cinema 30 speaker out should be able to handle that.
Here's a link to the
Philharmonic Audio HT Center mentioned. Small but well known company that make great speakers and the finish quality is very good as well.
Matching center would be the HTM2D if I have the year of your 803 correct so you may need to search for a used center or consider the
HTM82 D4 or HTM71D4. Rather expensive compared to what else is out there. There is the
HTM71 S3 which is much more affordable if you want to stick to B&W. Judging the room from the photo it looks like you will need a speaker stand and a way to hide the cables. You will want to check the total height of the speaker with stand to see that it fits below the fireplace. Something lower to the floor should be angled up towards your ears.
It's a beautiful room but what I see are a lot of hard surfaces. Have you tried the clap test to see how the room echos? An area rug in front of the main speakers can help reduce reflections from the floor. I don't think you are about to hang sound absorbing panels all over the room, but hopefully you have some heavy shades or curtains to cover all of that glass. Also, having the speakers tucked away into those recesses may have the best visual appearance but it is one of the first things people will recommend against for good audio. Consider experimenting with moving the speakers out into the room more if possible. I know that's not always an option with small children.
