I have been in your shoes!

Good call with putting in heavy drapes, it does help. For your windows, I would change out the single curtain rods for double ones, extend the length past the windows on either side, hang sheer drapes on the inner rod and even thicker ones on the outer. Make sure you get enough thick curtain panels to bunch up on either side, at least double what you have now in the living room.

Get plush rugs instead of the flat pile area rugs and put one in your dining, under the table. I hate to cover the tile detail but would sacrifice that for the sake of ears (and sanity).

You're right about leather not helping reduce noise! It amplifies it. Large textured throw pillows and draping thick textured throws over the backs of furniture helps.

Canvas art without glass is great too! To boost their echo stopping power, you can fill the empty space behind it with foam or cut a flat acoustic panel to size and put in behind it. I'd also put acoustic panels behind all of your current art work.