You don't need tape if your diagram didn't lie: ) That's 1/4 inch to a foot . Your sectional. Pull it away from the sun room wall. You can get a long console back there, closed sides. The dog wll like the hideaway. Put an outlet in a closet!!. That's where your Roomba goes- not hanging around in your great room!!!
Get a nice big rug..... Bunching round cocktail table, two chairs.....they can swivel!
Yes fill in the niches console, drawer chest...I would NOT build in. Use it for two great mirrors above, Lamps...
Tip? Find the rug you love.....and take colors from there, Go to loom.com : ) Worth waiting and saving for
Don't ignore small dressers as niche storage. West elm just for example, since I'm Lazy...
Bunch the round cocktaills WE for example
Add texture......big basket for dog toys, Pillows on the that sectional. Yank some color from a rug
Don't forget lamps....
Q