Topic: Level Maps from SVG
I just came across a post when looking for a plugin that imports svg graphics as sketchup shapes. In the thread there is a workflow for using blender to get it done.
http://productforums.google.com/forum/# fzFKgpNJWo
This will come in handy for making large levels. You basically go from a drawn sketch (without Sketchup) to a 3d model.
I used the free software INKSCAPE to make my svg file but you could use Adobe Illustrator also: