Hi MH (Mike)
Before putting up any more dampening lets control the energy that you have. Better to use an acoustical control system than a dampening approach so we don't loose music information.
Looking at this with all of it's objects my first thought would be let's go RT Squares. Count all your corners, mid-seams and main corners even in the dining area and tune them. Once done your main loading areas will be very controlled. At that point you could decide if you want to get even more tweakie.
I took this from my product page for you to look at.
When we listen to sound in our rooms we are listening to air pressure. Sound waves are not traveling in a straight line to our ears. There are 2 main parts to what the sound pressure (build up) is doing. One, pressure zones, the other, laminar flow. Once these 2 are under control by putting up the Squares the music will come to life.
here's the rest of the RT Square product page
I would recommend going with all Squares in your room the way it is. Don't really see a need for the XLT's. The Squares will have enough burn, however the XLT's are no extra charge so if you feel you might need more burn, go for it.