I added several options for art and wall decor to your shopping list, including mirrors and gallery frames.

NOOK
My preference for the nook would be the mirror on one wall, with the framed watercolor abstract on the other (on each of the short ends of the table).

I would either hang the 7 gallery frames directly above the TV as shown, or do three to the left and three to the right, and use the extra frame elsewhere in your house.

Here are a few options to style your mantel. I would arrange the candlesticks either in a row as pictured, or in more of a triangle grouping. I also added pillar candles to your shopping list. Both the vase and the clock pick up on the sea glass color you love.

Hang artwork 4-6" centered above the mantel and 2-4" apart from each other. It should be hanging at a raised eye level, so that you are starting slightly up at it. Command Picture Hanging Hooks would work great to hang the mantel art!

I added a few options for ottomans to your shopping list. If you do the smaller Annette Storage Ottoman, I would do two side by side.