I am currently using Virtus Walkthru for 3D conceptual modelling.  It
gives a blocky but useful view of proposed designs. Its interface is
simple, and you can instantly see what you've built. I made a Quicktime
movie of a walking path, which makes a small, fast preview for
presentation.

To get lighting and textures, I just work on a Photoshop version of one
view.
I haven't done much with other 3D program, because I think they take a
long time to actually render your design.

email me if you want more infor, have some better info for me, or just
want to share ideas.

Bill Sander
Wells Fargo Historical Services
[log in to unmask]