If you get bored of the SketchUp default effects, you can try this sketchy yet presentable effect by Heterarchy Ltd, it looks like watercolor effect, very soft, and feeling comfortable.
You can achieve it in 2 ways, either going to built-in plugin where is available from the top menu in window > styles >, there are few options that you can play with, and of course it is able to edit to your preferences, but some mapping you may need to do it in photoshop.
Touch-up in photoshop after exporting from your SketchUp, you may need some photoshop skills.
For me, I would prefer using built-in effect because it would save you a lot of time in photoshop if you have a lot of images to present, however, if you only have few nice images to show, please do not hesitate to do it in photoshop, it is a very powerful tools to enhance your presentation style and overall effect.
Images © Heterarchy Ltd