You'd like the shadows to grade to a darker intensity like a radiosity rendering would. So it will taste good like a cigarette should?
First, let me complement the wonderful dollhouse quality of this rendering - the aspect of the view and the scale of all the parts gives a wonderful "sitting on the desk top" sense and the lighting is well modulated. Users (and me) will appreciate you posting your lighting solution. The dollhouse feeling is from the forecourt - the overscaled roughness and reflectivity suggest an unreal model material and not a real base.
You can get graded effects by adding general lights with moderate fall off - they will begin to fill shadows with interesting varied light intensity. Put them under the ground. They will shine thru. And also brighten your eaves that are a little murkky.
I am getting great shadow interference using a second sun. Emulating the lighting on the distant planet Zebulon, the only planet in the entire galaxy to have humanoid-like life and binary suns: one, warm, like you've provided, and one at right angles that doesn't cast shadows - a newer sun that is a bluer color.
Dwight Atkinson