Zero threshold shower stall with bench if space permits. Comfort height toilets are nice too.

Consider their limitations and declining muscular strength that occurs with age. 1) taller toilet seat. 2)shower seat/bench (If either parent has Diabetes, then they may soon experience peripheral neuropathy, which limits their sensation in their lower limbs. you need to consider shower safety (wheel chair access
for a roll-in shower)

Two Bathrooms ?
Aging bladders cause urinary frequency and urgency problems, where as bowel motility slows down.

I suggest two big medicine cabinets (his and hers) and good lighting. Drawers in the vanity for storage are far, far more useful than shelves. The number of pill boxes, lotions and medical stuff just gets huge. As you get older, you need twice as much light to see the same things.

On the vanity, space for a hairdryer to be set down, a tissue box, an electric razor, a couple of battery toothbrushes, two kinds of soap (really), and a couple kinds of hand lotion. Get the toothbrush holder with cup space that goes on the wall. Put GFCI electrical outlets on both sides of the sink, again, his and hers, for stuff that needs to be kept plugged in or charged overnight. Use 4-outlets for each, not two. There will be a night light in one.

Apple-pie-order...either you're old like me or have lived with a wrinklie one because those are excellent ideas. Lighting should be especially bright and NO throw rugs for tripping, which means floors should not be slippery when wet.

Move the toilet fairly close to the door. Elderly people move slowly and even a couple feet less to get to a toilet can make life easier with urinary or bowel accidents. Think about how fast you run to a toilet when you get the flu, then imagine the same urgency without the same mobility. Caring for an elderly father, there have been many times I wished his toilet was not at the far end of the bathroom.

All the above suggestions are great. There are some great grab bars now available that look like towel racks.

Edithsmom: there's such a huge difference between what really goes on countertops and what is shown in Houzz photos. The current craze to replace medicine cabinets with wall mirrors eliminates a huge amount of convenient, eye level storage. People who recommend tiny vanities and pedestal sinks may not have had to balance a hair dryer, a tube of toothpaste and a set of contact lenses with cleaning and wetting solution bottles on the edges, let alone tried to keep a recharging razor, a Water Pik, and a nightlight plugged in at the same time when someone else wants to dry her hair. I've also seen what really happens when people get old: I've helped relatives and friends deal with older people moving out and moving in of various houses and apartments. Not everyone has a powder room that is used only by guests.

And I agree with you about the throw rugs and tripping hazards. I know some people get angry when the old rumpled throw rugs are removed, but it is better than getting that phone call from the hospital about the broken bones and concussions.

I took care of my increasingly frail mother for nearly 4 yrs. in our home. Ditto the "high rise" commode, we added hand rails to it later on. Grab rails placed thoughtfully for entry to the tub (we did not have the budget for "barrier-free"), a secure seat in the tub and hand held shower wand, as well as grab bars inside the tub. Make sure you have gripper safe matting (and keep it clean!). Motion sensitive lighting would be nice... it comes on instantly and it goes OFF if they forget to hit the switch. I often longed for a room specific heating element to keep the room cozy as I bathed her, on a timer would be ideal.

And make sure the bathroom is pretty. Nice towels, nice soap, and rugs/mats that are safely secured and not a tripping danger. Mum always noticed that the appointments were pretty.

Hands down the most painful experience of my life (thusfar). Nothing is worse than watching a much loved parent evaporate before your eyes. Nothing. Worrying about safety is not a burden you need to shoulder in such difficult times.

If you can splurge on heated floors - that would be a treat. Ensure you choose a non-slip mosaic for the shower floor, and I would advise against polished porcelain for the larger floor. I recommend a wall hinged shower seat, that can be folded down when not in use to allow more maneuvering space. A hand-held shower is easiest, both in case of caregivers assisting, or to simply warm up cold or aching feet etc. Have only one main mirror over the sink - mirrors on cabinets or on opposite walls etc can be dizzying for seniors, especially at night. Good luck! Feel free to message me with more questions. :)