Leave that space empty. Objects up there are dust collectors, and weigh down the appearance of the cabinetry. It is very difficult to achieve an uncluttered look with items in that space.

If you are able, try to have cabinets that go up to the ceiling. Don't worry about not being tall enough to reach up there. Most women can't reach above the second shelf regardless of the height of the cabinets.

In our previous home, we had upward facing lights, no decor. Current home - nothing at all.

I've been trying to figure this out for 20+ years! Our kitchen has vaulted ceilings, probably 20 feet high in places--so there is a lot of space between the cabinets and the ceiling. Yes, I have some dust collectors up there. Still trying to figure out the right answer to this!

Nothing at all.

Above the cabinets?
More cabinets.
Even though I'll never put anything in them, being only 5'2, I like the look and it negates that empty, last minute thought-ish space up there. Smooth look with cabinets.

You'd be shocked at how many you can stick up there.

Sorry but I need to ask : do you want to / need to keep that empty space? As the others have said, it does become a nesting [place for dust bunnies, so if you can add another (even small / narrow) cabinet, would second doing that.

If you can't add another cabinet above (e.g., existing boxes that you're keeping) and want to avoid cleaning dust bunnies, here's a very low-tech solution:

The top of cabinets happens to be the width of a paper towel. Run them along the entire top of your cabinet runs. The trim/crown should completely hide it from below. After a time, remove them, toss, and add fresh paper towels. It sure beats scrubbing. And FWIW, there's surprisingly little dust/grease on the old paper towels.

I have a string of rope lights up there on a timer--looks warm and cozy in the evening. Also the largest of my collection of pitchers--I'll attach a photo. Yes, they get dusty but I don't actually use them, so every five years or so they get taken down and washed. I can't imagine scrubbing the top of the cabinets. I'm sure some of you think it looks "cluttered", but I like it and I'm not changing my cabinets.