FrameForge 3D is a fantastic choice. Their version 2 (they're on 2.5 now) blew the roof off of what you can do in a genuine, previz, 3-d environment.
What has me all hot and bothered is that I recently had a problem and they fixed the bug and posted a new build within a 36-hour period of time. Excellent customer service.
Highly recommend them if you are looking for a reasonably affordable SB app. (And , no, I have nothing to do with the company, nor do I make a penny from them - just trying to pass along a great resource to the forum).
KH