Thank you all for the kind words. It means a lot coming from a great SU community.
I tend to go straight from SU/Twilight without any post production. I do use the curved tree lines in the background and mixing in freestanding trees for some depth. The long render times usually pop up when I turn on the lights for the night views. Also, depending on the client, some of these get printed on poster size presentations.
Here we go, jumping way out of my comfort zone and sharing a little bit of my work. I am an avid Lurker reading through posts, browsing the incredible work that is posted by everyone and constantly picking up new tips, tricks and resources. As a sign designer, one of the best ways to show the client the dimension, scale or lighting of a sign is through SU. One downfall is the very short turnaround time for most of these projects. For the most part, I can only afford to spend 3-4 hours in SU which is why the backgrounds and landscaping all appear pretty similar. The nice part is that I can get it all set up & let Twilight burn overnight. Wow was that longwinded. Anyway, I hope you enjoy and if you don't hear from me, don't worry, I'll still be lurking and learning.
You can also try exporting your DXF file as an older AutoCad version. I export all the way back to AutoCAD R2.5. It's not perfect, but it is much better. Adding extra points to the curves before you export the DXF will also tend to help