How high are your ceilings? Are you doing a steam shower or very tall glass?

I personally don't like tiled ceilings, but there are situations where it is a must -have.

9ft. Will be enclosed with wall and glass door. We def like a hot steamy shower.

We just did ours and tiled it. 12 X 24 tiles they cut to 12 X 12 and laid them on the diagonal.

@clt3 Thank you. This is helpful!

If your walls are not completely, 100% square you are going to begin to have slivers of tile that will emphasize how out of square your walls are. What if the grout lines don't line up from sides to ceiling?

Why do you think ceilings are NOT tiled except in steam showers? Because walls are NEVER perfectly square.

@BeverlyLADDeziner good point, and one I hadn’t thought of.

i agree with the issue of the grout lines aligning so that's certainly a reason to not do it. Although it sounds like you (husband) are hoping to do a different size tile on the ceiling than the walls. If that is the case, the grout lines won't line up but it may present opportunity to make it look intentional if they don't. That's seems to be the case of @clt3's ceiling being on the diagonal. Intentionally not lining up.

FWIW, I just gutted a midcentury bathroom that had tile on the low shower ceiling. It also had tile on all four sides of the shower so sometimes a true midcentury look isn't so good.

If you google "shower with subway tile on ceiling" quite a few images pop up. Some good, some not so good. My concern with what you're describing is that you'll wind up with four tiles in a small space.

Can you post pictures of the floor, shower wall, shower floor and desired ceiling tile?

Here's one with a lot of different shapes and size tile and they have four but three are basically white and mostly white mosaic. The shading and different shapes of tile add the interest.

The house I grew up in had tiled ceilings over all the bathtubs and showers. The tile was laid on the diagonal. If there is a matching tile in a square format you could use that.

It's possible to lay tile on ceilings in a way to compensate for any out-of-squareness --just like they do on Floors--frequently, because a room is not any more likely to be perfectly square on the floor than it is on the ceiling--and that is to Not start at the wall with a full tile that may require a sliver at one end if the wall tapers away.

A good tile setter will try to figure a shift in the layout that will avoid slivers if things are not square:

They should not do this:

They Should try this. This isn't centered and it's just a quick mockup, but the tiles would be shifted to avoid slivers in a focal area.

Thank you so much. I ended up ordering the tile last night and we are going to use the same 4x16 in a vertical straight line as we do on the walls.