How about an arbor over a terrace of some kind to fill in the indented corner on the left? Something attractive for the windows to look out on, and will make the house more substantial looking. That corner faces south, right?

Terrace like with a seating area or something? There's an idea. Yes, the front of the house faces south. View from the windows isn't too great here (below), so thinking about what I can plant at the property line to sort of block that. Have to work around septic tank and electric lines here, though.

If it had seating, you'd probably use it in the morning, and yes, you'd want to enclose the view of the neighbor probably. An arbor could still be attractive, and improve the view from inside the house there. What are those rooms?

I imagine you'd want a terrace at the back to look at the mountain. Where does the sun set?

The rooms are bedrooms. The 2nd view from the window above shows where the sun sets, over the neighbor's house. I love that you call it a mountain. :) To put it in context, this is the one area of the home that is set close to neighbors, so I'm trying to landscape it to look nice from inside, and also from the front, but overall it's probably the least important area now that I think about it. Pics below for context.

View from the back deck

View from the front deck

Area around the house is nice, but the actual landscaping is non-existent! And it doesn't help that the siding color is blah!

Yes, shutters! It's on my list. There were some ugly maroon ones when we bought the house. Took them down because so many wasps and bats residing in them. Looking forward to replacing them just on the front for curb appeal!

Your perennial garden is just so pretty! I love the colors and plant combinations. How about a mixed tree/shrub border to block that view you don't want of your neighbor? All the other views are spectacular!

I am also a big fan of flowering trees. Maybe a couple of Cornus kousa trees? I think shutters could be difficult since there is so much variation in the sizes and shapes of your windows. I would just trim them out with wider trim (which could be in a color other than white if you like). Then, I would just add some trees to camouflage that irregularity. Oh, just had another thought-how about extending that deck to left (as I look at it in the picture)? Then, put a tree near the corner there and another back near the corner of that small extension. Add another to the right past the perennial bed. Can you tell I love having lots of trees? :)

One last thing, I don't think the house color is bad at all. It is a pretty house!