We're going to do the same thing. Right now we have regular height cabinets with no soffit above, and we store pottery collection, pictures, baskets and a bunch of other miscellaneous stuff up there, but it's hard to get at. And if we want to use something from up there, it always has to be washed first.

We are just finishing our kitchen and have a 9 ft ceiling in there. We did stacked cabinets and we are using the upper cabinets for holiday dishes and stuff we don't use alot, but still stuff that I will use. I am 5'7" and use a 24 inch step to get to it. No regrets and it looks amazing!

If you don't go all of the way to the ceiling, will you still have enough storage space for all of your stuff?

We also have 9 ft ceilings and just went up to 8ft with our cabinets. We have tons of storage with this new layout, so going to the ceiling would have been a big waste of money for us. We put that money towards other features in the kitchen. We actually did a "cityscape" look, where we have our uppers not as high as the tall cabinets. Topped with crown molding, I think it looks rather nice. It doesn't bother us as much as it does to other folks to dust the top of the cabinets once every blue moon.

Stack some cabinets, and don't stack others to make the room more visually interesting.

Also by using glass or frosted glass in the highest cabinets you can turn them into light 'lanterns in your kitchen.

Thanks for the responses. I do like the idea of stacking some cabinets to the ceiling and not others to create some interest. My layout has a door that essentially divides the cabinets into 2 wall areas that form an L shape. one will have the fridge and the other will have the cooktop and wall ovens. Taking the fridge wall to the ceiling should be a good look.
We are going with frosted glass front for the uppers. A contemporary look with aluminum framing. Lighting those could work well.

If you go to the ceiling with all the cabs you can also create visual interest by choosing which cabs to put glass in and which not to. You can then use some of the non-glass uppers to store trays and platters.

How tall are you? I'm 5'8" and can reach the vertical tray storage and the first row platter storage flat-footed, and the 2nd row platters on tiptoe. Since the fridge/pantry cabs aren't recessed back over a countertop like regular uppers they're a lot more accessible.

So depending on your height you may be able to reach your over-fridge/pantry uppers without a step stool (unlike regular over-cab uppers which are generally a little higher plus set back).

We store less used serving pieces and food items at the top of our cabinets. Fortunately DH is almost 6'4" so that helps, but I also have a step stool nearby. Personally, I prefer cabinets to be at the same height, but part of that is it goes best with our vintage home.

These photos were taken after we put stuff in the cabinets, but before we organized, but you get the idea.

@1929Spanish - what size are your upper cabinets? Thanks!!

@flazoom - what did you end up doing in your kitchen? i'd love to see a photo! Thank you!!