Actually, I liked my old soffit in our kitchen a lot. We had a tiny house, with just a "great room" - our kitchen, dinning room & family room was all interconnected.
The soffit provided some separate for the kitchen, and the contractor recommended hanging pendant lights from it.

I think it can look really cool :-) Here is a pic of our old house, with the remodeled kitchen. We wanted to orginally tear down the soffit to allow for a bigger kitchen but couldn't since it was a load bearing wall. In the end, we were pleased we didn't!

That looks great! Very similar to what we are thinking. Anyone else have examples good or bad to share?

You can also do soffits so they are flush with the face of the cabinet and make a minimal statement.

If the kitchen is open to both rooms it may make design sense to do them in the kitchen to tie the kitchen to both the 8 foot great room and the 8'6'' dining room.

I tend to do soffits more often than not because I don't care for empty space above cabinets very much, but I have treated them in a number of different ways including finishing them the same as the front of the cabinets and adding moulding to make them disappear-- all the way to having an obvious soffit.

While I don't miss my soffits, they can look good if done right. One of the first kitchens I bookmarked on GW was Tisker's kitchen. She had a similar situation with ductwork and added soffits. Scroll down for pictures of her soffits.

You may also want to Google gardenweb soffits. I remember a thread a few months ago that had a lot of pictures of remodeled kitchens with soffits.

Here is a link that might be useful: Tisker's finished kitchen post

I had a beam to deal with and did soffits on the opposite side because I am a nut about symmetry! My cabs sit flush, but they are in a high contrast color to the walls. Not great, but I am driven by function. :-)

I looked at your layout pics and I think that if you have to have a soffit, the treatment you've already come up with is a pleasing one. I much prefer that look to the more basic look.

We had to have a soffit on one wall and decided to turn it into an architectural feature:

I don't know if an arch would work on your fridge wall, but it could look really cool with your columns - something like this?

The pictures look good, the soffit ceiling looks sculptural.

However, think hard about ceiling height. I can't tell if the ceiling in the kitchen is 8' or 8' 6''. Suppose the soffit takes away 1'. A portion of ceiling only 7' or 7' 6'' high risks feeling claustrophobic. Vaulted ceilings are usually tall spaces. A vaulted low ceiling is, hmm, anyway you'd want to be sure that was an intended effect. Don't want to end up with a crypt, or hobbit-hole, feeling.