Sketchup is probably your best bet if you're looking for something free. Chief Architect has a variety of software available at different price points that would allow for quick ceiling designs.

Sonia, maybe this will help you, size of the room and layout is per your drawing... coffered drop is 6" with 9' ceiling showing.

Thank you so much Gn Builders. Is the 9' to the top of the ceiling or bottom of the coffer? I have a 10' ceiling. In your opinion, for a 11 x 14.5 room is this to imposing?

Thank you HG3D as well.

The image is 9' to the top of the ceiling with 6" drop, depends how impactful you want that to be, for a 9' ceiling is usually 5-6" drop. With 10' ceiling you can do an 8"-10" drop, the smaller the drop the less impactful it will look.

Best way to get the effect you're after, is take a few larger sized cardboard boxes cut them into lets say 4' long by 2" strips, and make a template of the size drop you need and see the visual effect. We tell our customers to do that so they can actually see how this will look. If you make one box and tape it up there you will get the idea. Here is something how to make a template, this is for a 6" drop.