Light gray grout.

No tile at all. Smooth wall acrylic showers/tubs are much easier to clean than tile with grout. They come in many colors and designs. Same with no tile on floor. Shower curtains are easier to clean than trying to keep glass clean. You just toss them in the washer.

Are you just replacing the floor?

Everything. Wall and floor tiles.

Make sure the floor choice isn't too slippery. Large tiles mean less grout, but also more slick.

What are you looking to replace? The whole bathroom or just the shower and floor? We need to know in order to make suggestions.

The walls of the bathroom itself, not the shower part, do want then tiled as well, or just painted? If I could do anything I wanted in my bathroom, I’d do the whole thing in solid surface.

Choose something with good slip-resistance.

https://www.daltile.com/why-daltile/innovation-and-technology/stepwise

https://www.armstrongflooring.com/commercial/en-us/products/srf.html

I've always envisioned a stainless steel interior, walls, ceiling, cattle grate floors. All SS. Just hose the place down. My dream house?

Everything. Wall and floor tiles.

Do you mean tiles on the walls and floor of a walk in shower? Tiles around an existing bath tub? Tiles around the sink area? Are you open to non-tile suggestions or is there some reason you want tiles?

Sorry, posted in error. If it seems at all likely that either parent may need a wheelchair someday, the Transolid shower at Bath1.com is better, at 37.74” deep. Here is mine

Personally I do not like acrylic or plastic of any kind. It just seems cheap to me. Have you looked into Neolith or sintered stone. It's a porcelain product that can be used on shower walls with no grout, but looks exactly like marble. It's not cheap, but it looks great.

100% use an acrylic insert or solid surface if your primary concern is ease of cleaning. No, they are not the snazziest design choice, but it's super simple to keep clean. No worrying about moldy grout and replacing caulk/silicone, etc.

I have a curbless fiberglass shower. It's genius. It came complete with shower rod and grab bars, for maybe $800. It takes up the same space as a typical fiberglass bath/shower combo. For luxury, I have a rain shower head and a heated towel rack (which might be a nice touch for easily-chilled seniors).

I sometimes vacuum the shower. That's how easy it is to clean. No grubby grout. No slick floor. The shower curtain enables a caregiver to help with washing.

I was really unhappy that I could only afford fiberglass. Resisted like crazy. Ha! I love it. I'm so glad I didn't spend more on the shower: I would have liked a custom shower only marginally better.

I HATED the Kohler curbless showers: they look dated and gloomy. (I was in the market just 2 years ago.) Because I yielded and went with the fiberglass, my budget could go to something else. And, no, it's not ugly. My bathroom is bright and light.

I did have an extra light fixture put over the shower for safety reasons as well.

If you can, I also recommend lowering the light switches, so they aren't such a reach. All faucets should be single handle and no twisting. Separate hot faucets readily burn. Twisting is hard on arthritic hands (even hands that have keyboard overuse).

Some of what I'm seeing upthread would be a nightmare if the user has balance, sight, or even minor cognitive issues. I have none of those, and I'd get dizzy with those patterns, like the one with the marble-y look. No, no, no, and NO for aging in place.

As for the floors..... gosh, those would mess with depth perception. Scary.

I love acrylic tubs and showers they are super easy tokeep clean and always look good. A simple alerge format porcelain tile on the floor I like 12 x24 and if you want to tile the shower the same tile in there . Use matching grout not white and get a squeegee to use after every shower .

Easy to clean? Single sheet flooring, acrylic/fiberglass/whatever plastic is being used now bath surround/floor. Shower curtain. Skip a tiled backsplash behind the sink- use a solid backsplash. Keep the bathroom walls smooth, skip tiling or wainscoting up. The less lines (like grout lines and wood grooves) there are, the easier it gets.