There definitely is a trend to finish cabinets to the ceiling. Though I think it gives the kitchen a much more finished look to the cabinets overall, it comes across a tad heavy to me (especially since we're looking into black cabinets). I also don't have a lot to display (minimalist).

Has anyone ever seen a unique way of finishing off those last 15" for a 9' ceilings?

Or clerestory windows on top of the cabinets.

39" with 15"s would take things to the ceiling if you prefer to have the space for lesser used storage. Use the Ikea aluminum framed ones for interest if you're doing Ikea, which I think you are.

You can also use the negative space as a portion of the design. Deliberately use short cabinets instead of taking them close to the ceiling. 24" high ones are often done, so as to get a more horizontal line happening. It's especially effective with horizontal grained woods. Or you can stack two 15" tall cabinets instead of using a 30" cabinet.

Or, you can do like I'm doing in my new office that I designed and do stacked 15" cabinets in different colors. You could do black, white, and aluminum and have 45" worth of cabinetry then do some molding or uplighting or both. In my office area, which took a big hit from the budget, I'm doing stacked two colors of 12"x36" cabinets to the ceiling in the middle of the run, then I'm swapping the doors around to create a sorta checkerboard effect. It's modern and textural. I just ordered the cabinets, so it's no where near being actually physically done, but I can post a pic of the rendering on Monday if you're interested.

In your pictures like I've seen in the majority of modern kitchens, there are no windows intermixed with the windows. We considered not having windows just to get over this hurdle but having the natural light throughout this new kitchen is VERY important to us.

I'm thinking that having 9' ceilings with new windows and trying to get that to not only look good in the kitchen but also the adjacent kitchen dining area, is a MAJOR struggle.

Heck, do the whole wall in glass block!

If you don't have stuff that you want to display behind clear glass, I would assume you could find glass with some kind of pattern or finish so that you'd get the light effect of glass without having to look at stuff that's not so pretty.