Good idea for a thread, I was looking for this info myself recently...
I tried out Draftsight for dwg's last night, it's free and was ok but I didn't find the interface very intuitive. I'd rather use Illustrator which I do have although Illustrator is far from free.
I didn't think Illustrator was thought of as a CAD program, are there any gotchas with using Illustrator to design cases/plates for lasercutting?
The one time I tried to use Illustrator to try to edit a plate file, it came up with some message about scaling that I didn't understand. I'll have to try it out again.