quick architectural sketches

until recently i have used sketchup to produce quick colored sketches of concept models for presention to clients.

now i want to see what i can get out of blender.

the idea is to produce quick but effective sketchy renders with (hopefully) a watercolor look. the process musn’t take too long because the client may not even like the concept. so renders of a few of different concepts can be done in a reasonable amount of time.

this is where i am at so far.

minimum detail in the model
simple materials with cloud or stucci textures
sun makes shadows
glass with ztransp only
then topped off with overshot freestyle lines (using current freestyle build)

are these renders any good? how can i make them better?