This article may have points you hadn’t considered.

https://jillianlare.com/living-in-place-bathroom-design/

A zillion articles on here covering what you need to know (including sinks):

https://www.houzz.com/ideabooks/query/universal-design-bathroom/nqrwns

The UD code, if you want some light reading:

https://code.universaldesign.org/chapter/bathrooms

We built our theoretically-forever home incorporating a lot of the UD principles for aging in place. You need to think not just about the bathroom but EVERYWHERE in the house - the width of hallways and doorways throughout (inc the front door), senior-safe flooring, extra lighting, and so on.

As an older person I like having counter space to put thins on for personal grooming. There are vanities designed to accommodate a wheelchair but that section is lower than the rest of countertop height. As far as the, no slip porcelain is the way to go, built in bench and a grab bar on each wall. Make certain the shower controls are easily accessible without having to step into the shower. You are great people to do this for your MIL.

Thanks for the advice. We had already incorporated a lot of the suggested things but there were issues I hadn’t thought about such type of faucet handles and placement of the shower controls.

We had already planned for a curbless shower with bench and handheld sprayer. The toilet will have a pony wall on either side to mount gab bars. The contractor suggested switching out the door between her bedroom and the bathroom with a wider pocket door to eliminate the door swing. We’re looking at either a wall mounted or pedestal sink and an armoire or dresser for storage. We plan to reinforce the back wall for future grab bars.

The contractor needs to be done by March since he has already scheduled a huge job for then. I plan to order only in stock items.

Once I get a space plan from him I’ll post it for feedback.

Oh, a few other thoughts:

I learned a lot about grab bar placement too. Post a simple sketch of where you intend to mount grab bars - now or in the future.

Light switches - get rockers instead of toggles.

Chunky items are easier to grasp than slender ones when you have arthritis - knobs, bars, handles, if you have a choice between skinny or fatter, get fatter.

When you get older, sometimes the urgency to go comes on quite quickly. Closing a pocket door can take more dexterity and time, whereas throwing a door closed can be accomplished easily. Ask her - is she the kind to go with the door open or would she always close it! If you decide to have a swing door instead of pocket, have it open out instead of in to the bathroom. If she were ever to fall in the bathroom and block the door she could become trapped inside. Yes, my dad confessed to me this is one of his greatest fears about aging!

If she ever needs incontinence supplies they can take up a LOT of cabinet space. Here's to a vanity instead of pedestal. Here's to room for a larger trash can too!

Consider a bidet seat. I'd put the grab bars in now.

I actually think as close to real ADA requirements as possible is the way to go those guidelines are great when thinking about aging in place . I am thnkfully close to 80 but very fit and healthy but who knows what might happen. The bathrooms need to be large for ADA and that is the first thing needed to be figured out in most homes .. Grab bars a must and I garee figure those out for the person you are doing this for . all of those need to be figured out before installing anything . There is lots of info on the net regarding the ADA rules and IMO follow those closely

The bathroom is quite long but not very wide.

How wide is it?

So glad I stumbled upon this. Recognizing this post is months old but @tcufrog - any photos of your (possibly) finished project? @kendrah - great advice!

Unfortunately, only the floor and shower are done. We’re behind because the tiler had a family emergency. He’s an excellent tiler so my contractor and I decided to wait for him.

Thanks for the quick reply! Sorry to hear about your delay. We start construction in a few weeks (moving in my parents - one with dementia). Before the planned move-in, I had envisioned the bathroom as a showstopper jewel box of a room - zellige tile, saturated color. Not! Porcelain tile, light color - has been strongly recommended for shower wall, bathroom wall, floors etc. Would you mind telling me what you chose?