The ceiling immediately overhead was charcoal with rings in varying shades of brown radiating across the living room and into the kitchen.  

We personally like the slightly darker neutral color, higher end remnants but the darker color is because it hides stains better in the rentals.If laminate is not worth the cost/effort but the carpets are really worn you may desire to look at what is available in remnants in your area. 

Different shades of green and yellow.

Carpet just stains too easily and needs replacing to often.I also use darker paints for the walls and skip the whites and creams.

It will get every shade of opinion on turnkey investing imaginable right here on BP.  

My personal opinion is that it will look really nice if you used a light shade of gray paint on the walls to bring it all together.

We use lighter shades such as Popular Gray and Eider White, by Sherwin Williams.

The higher walls shaded by the eaves remain the same color, while the lower walls that gets the sun gets lighter and lighter.  

Take good photos, lights on, shades open, etc.

My guess is the tree drips water and organic material on the siding after a rain and then shades the side.