Crown mold in the kitchen

I have a large kitchen and dining area in a 70\'s style ranch home. I am adding crown moulding, I like the look of 6 to 8\" mouldings but I am confused on what to do with my soffits. They cover a large area of my kitchen and are approx 12\" in length. Would that look odd doing them with that thick of a moulding? It seems to me it would but it would look strange doing a smallers one on the soffits too? Am I limited in the size of moulding to use because of the soffits I hate?

If you have 9' high or higher ceilings, I think you could put a tall molding on the soffit.  The 6" to 8" is pretty tall, you might consider a 5" to 6" instead.  What ever you do on the walls other than the soffits, I think you should do the same on the soffit.  It would look odd to not do the same on all surfaces.  Remember, the molding you put up will reduce the feel of the size of the room.