My Home Theatre Room Challenges - Is It Worth It To Upgrade Speakers

I have a very nice 2-channel stereo room where I love to listen to music by myself.  I am happy with the equipment and set-up in this room (at least for now).

Our family room (on the other side of our home) serves as our Home Theatre room and my wife and I watch a movie in this room together almost every night.  We recently upgraded to a Sony 83" A90J television and we love the picture quality.  

I consider sound quality to be just as important as picture quality when it comes to watching a good movie.  The 5.1.2 sound equipment in this room currently features:

• Yamaha RX-1080 Surround Processor
• Paradigm Prestige 15 Front Speakers on stands 
• Martin Logan ESL Center Channel
• Polk PSW1000 Powered Subwoofer
• Paradigm Millenia 1 Overhead Speakers
• Polk In Wall Rear Speakers
• Room size = 20' wide X 18' deep (no rear wall)
• Ceiling Height = 20' tall

The room has two big challenges:

• WAF is critical - this is our family room, having front speakers that sit 4' out into the room is not going to happen
• there are two couches that sit directly between the Front L&R speakers and our two primary listening chairs.

I would love to make a big and impactful improvement in sound quality in this room. I am currently considering replacing my two front main speakers (Paradigm Bookshelf 2-way speakers with 6" drivers) with full-sized speakers.  I am considering speakers, like perhaps a nice used pair of B&W 803 D2's, with the intent to dramatically improve base and be able to better fill the large room with sound.

Question:  Will the two couches block the sound improvement that I am trying to achieve?  (Right now my bookshelf speakers sit on stands which allows the soundwaves to not be blocked by my couches.)   Does this upgrade of front speakers in my large room seem like a logical first step?  I would love to hear from someone else who possible made some similar changes.

Thanks!