Cast shadows are a outstanding way to evoke a notion of sunshine in your rendering, so make the most out of them. Where you have a house or building, by all means push those trees closer in to give yourself an excuse to lay cast shadows over the walls and roof - it will breathe a little magic into your rendering.

Cast Shadows

Cast Shadows

Another thing you can do, to utilize cast shadows, is place a Gobo off screen. A Gobo is a  partial screen used in front of a spotlight to project a shape. Here is a great resource for some free Gobos: 

http://www.cgtextures.com/

 If you have any question please, contact me, and I'll reply as soon as possible.