Personally, I see no reason to hide W/D from guests, and trying to do so will create more inconvenience for you, no matter how you hide them.

How often do you do laundry, and how often do guests use the guest bathroom? If you do laundry more, then better to have it more functional as a laundry room.

Shoji screens seem like they might get damaged since the washi paper is so light, and there will be water near them.

Since you're going to build a counter top, is there a reason that you wouldn't want to use sliding doors below it, or folding doors? See some sliding examples HERE.

See some examples of cabinets hiding a washer/dryer HERE.

I did a bunch of research on shoji screens looking for doors for my closet. I still haven't committed, but I found this company and was really impressed with their product and customer service.

They have options for the "paper" portion (like fiberglass, acrylics, coated paper) that would be more practical in your application than the traditional paper.

I agree with hiding w/d from view. There is nothing about looking at them that is pleasing to me.
Cherry Tree Designs

IKEA has sliding doors that might work or you could go the sliding barn door look where tracks are on the outside.

Since the W/D are now where your tub once was, why not put up a pretty shower curtain that can easily be opened when it's laundry time? I'd probably use two panels with hold backs on each side to keep them out of the way on laundry day, but I think that's the most logical solution and your guests would have no idea you are hiding your W/D from them.

The washer and dryer are deeper than the tub. They sit partially under a window so I can't do anything that would extend to the ceiling.

They wouldn't have to go to the ceiling. I've never had a shower curtain that did. Can you share a photo of the room?