Not sure where you're located, but a gravel driveway may help to soften the house versus asphalt or concrete. Soften up the area with grasses. Here's a link to a photo of grasses with a hot color palette http://www.spacemakerpress.com/catalogue/catimages/st05imgb.jpg You can always choose a more muted color palette as well. I would definitely tier the plan heights so they're taller against the house and gradually get lower. It would help to bring the house to human scale and not appear towering above. The pathway could be in a natural stone - the same color as the gravel driveway (if you can do gravel).

For chair scoot and sit space, I'd follow the guidelines for a rug - 4' all around. Then you want to be able to navigate around the table while people are seated, so add another 18" all around. Are you locating the table at the end of the galley? Maybe you could use a banquette on one side or in the corner https://www.houzz.com/photos/3rd-street-bungalow-traditional-kitchen-austin-phvw-vp~214425

Hi definitely remove the x bars on the deck balustrade. Landscape close to the house so it grounds the house. Trees will make it look less bare. Chose some that work for your area, that are evergreen, and are not going to grow really big. With a really plain house - dark colors will make it look better. Dark Grey, or black with a warm tone so it doesn't have a blue undertone in it. Make sure it is a warm grey or black. Use green foliage around it. Paint out the pergola in the dark grey too or white if you want a different look. Fill in the balustrade where the x is removed with plants in front of those areas. Grow a vine up the pergola that is nice.

I am planning to add scatter cushions and think if I do a pair of larger ones for each end so they go over the arms to creat height at each end, and a couple of smaller ones, I want to bring some colour in too. I do like the idea of a larger side light at either end to, Switching the sofas is going to be my final fix if all else fails!!