Senior-friendly bathroom remodel?

grab bars in the shower, and one outside the shower. ask a social worker to come by and help with these questions. side diaganol near the shower head, straight on when you enter. take into consideration your person. How tall they are, what is their mobility, etc.
a portable shower seat... some geriatrics feel free to poop in the shower... and is more comfortable for them when dementia hits.
so a porta potty shower seat with open "seating" may be considered.
Do not put grab bars on the floor of the shower. That doesn't do anyone any good.. (joke)
Maybe a grab rail to transfer from shower to bathroom counter would be good.
Take into consideration how big this bathroom is, how long this person will be there, and able to transition from sink, to toilet, to shower on his/her own. Are these good for a healthcare person to help patient utilize them..

Oh bless you! Bless you for thinking this through BEFORE you go ahead and have the work done - trust me, you would not believe how often it seems not to occur to people that such might be a good idea.

To determine the position, height and type of grab rails/bars, walk it through pretending you are your various seniors. Where does your hand naturally want to be? When you're showering, and perhaps having to balance, what will you hold tight to? Will you be able to install a drop-down shower chair? For all of these items, you also need to be sure that the walls/floors they will be fixed to are of strong enough construction. The freestanding ones do come in very sturdy design; their other advantage is that they can easily be positioned to suit a person's needs - one-sided weakness after a stroke, for example, or having to keep one leg out of the water, or needing a caregiver to wield the shower head. When looking online, try to match the choice to the person's build and bottom and do not be tempted by false economies. A forgiving surface to the seat is important too: arthritic or recently repaired hips make hard plastic extremely uncomfortable to sit on.

"Comfort height" toilets are ideal UNLESS you have a preponderance of tiny frail ladies. Dangling feet do not make such a lady feel very secure, nor are they any joke if one is constipated. You can get those steps that toddlers use when they're brushing their teeth, though, which would solve that problem.

Anticipating dementia: taps should look like taps (faucets, I mean). Not dolphins, nor brutalist stainless steel bars, nor "look no hands" magic props. And it should be easy to see which is Hot and which Cold.

Handbasins should be large enough, and have ample shelf space for: soap, 2 x flannels, nail brush, razor, shaving brush, plastic mug for rinsing after dental care.
Ideally, there should be space under the basin for the person to be able to sit comfortably using a perching stool.

The floor should be non slip.

The lighting should be really good.

There must be ample towel hanging space.

What range of seniors are you catering for, if you don't mind my asking? Any significant existing mobility or health issues?

OK . .here's my list:

Two separate shower mixers in a curbless shower. One 3' high and the other adujustable higher. Bench or chair.

Wall hung toliet - make to ADA height (this makes it very easy to clean under it, or place a commode .

GFI near toliet -Toliet seat washlet (bidet sort of)

Floating vanity cabinets. Foot, walker and wheelchair clearence underneath.

36" wide or wider entrance to area.

Sinks should have single lever misers that can be pushed with hand, instead of grabbing (for arthritis or shakes)

Space for tall closable trash bin for diaper disposal.

Open shelving storage for easy to reach needed items.

I put in an entirely new bath.  I did not go with built in shower seat, so now a roll in chair can go in.  At first, mom used freestanding, but now transferring is not easy, so I would rather move her into roll in shower chair in her room and wheel her in.

I had a shower put in my powder room. Worked because my laundry room was next to it.

I had a great contractor who had done many bathrooms. Because Mom would need to sit to have a shower, the bar on the wall was just at sitting level but high enough when she stood she could still hold on. This bar ran horizontally. There was a vertical bar she could grab on to going into the shower. The shower itself has a 2 or 3 inch lip. They do make them floor level. I use a shower curtain. It has been discussed before that doors maybe dangerous because people tend to hold on to the towel rack/handle which is not made to support weight.

I also chose to only have one set of shelves in the corner of the wall where the shower head is. I was afraid Mom would slip backwards and hit her head on the other set of shelves. It was recommended that no bench be installed. The contractor said people had complained they couldn't get to their backs to wash. I had a shower chair for Mom. I also had a handheld shower head. What is nice now is that you can get the regular shower head and the handheld in one. There is a knob where you can shut off one to use the other.

Toilet, I am short and have both a high one and short one in my house. The short one is nice because my feet touch the ground which with the higher toilet, just my toes. It is harder, though, getting up from the shorter one which was already in the bath I had the shower installed. I did need to get a high riser for that toilet. Found one where the seat was hinged for easy cleaning and was able to be permanent. You need to watch high risers that don't connect with arms. They tend not to be stable. Hopefully, they are obsolete by now. Our clients never liked them. We always recommended commodes over the toilet for people needing stability and arms.

Counters are pretty standard. At my Moms AL there were no cabinets under her sink so a wheelchair could be pushed under the sink. That, to me, would be where the height would make a difference. In my family its short me battling against a 5ft 10 DH. He is always putting things at his height forgetting about me.

I'm popping back in to mention that you should include some kind of accessory heating in your plans, even smaller bathrooms can feel chilly, especially to older people.

I would put a grab bar vertically at the shower entrance and another horizontally along the back wall.

We got the "tallest " toilet that is on the market, but my mom still needs an extender.

A shower head with a removable spray nozzle is a huge help if you're going to have to bathe someone else.

Regardning the chair...one that's attached is more stable; but being able to move the chair is convenient too, especially if you don't have the shower spray nozzle.

If you can: consider widening the door (s) to the bathroom, so you can at least get a walker comfortably into the bathroom. If not, consider grab bars going into the bathroom along the walkway.

My mom has all kinds of safety equipment IN her shower, but nothing to help her GET into the shower, if you know what I mean.

Someone told me to imagine starting to fall in the tub, and where you instinctively put your hands to catch yourself would be a good place to put a grab bar.

My dream bathroom would be a complete wet room that is 100% accessible for anyone in a wheelchair. In my opinion an adjustable height shower chair is superior to any built ins, get something with a back and arms too. Put a diagonal bar or an L shaped bar on the back wall and a horizontal bar at the entrance, my mom was always looking for something to hold by the taps so maybe a small bar there too above the taps. Bigger/longer is always better and also more flexible. There are recommended heights but we just placed the shower chair and eyeballed the most logical positions. A hand held shower on a slide bar is a wonderful feature. 3M makes inexpensive no slip shower strips.

Toilet height is going to depend on how tall someone is, instead of opting for a higher toilet may people just use an extension or place a commode over the toilet with portable arms. Grab bars there can be a problem if walls are not withing easy reach, there are nifty systems available that attach on either side of the toilet and can fold up against the wall or very nice looking grab bars the can double as towel bars, don't make the mistake of placing a regular towel bar anywhere that it might be used as a grab bar since they are not sturdy enough. And of course finding studs is always a problem if you are not planning on opening the walls. One thing that was invaluable for me once I was assisting mom was something for her to grab directly in front of the toilet, I purchased a Superpole with a swing arm because there was no wall available.

Make sure your door is wide enough for a walker or wheelchair. Think of anti slip flooring. I opted for a normal pedestal sink as being multifunctional, a wall hung sink would have been better but also much more expensive.