Is this location in US? Is there any storage in the alcove that the entry door opens in to? If no, what‘s in that space? Is there a mirror inside the cabinet over sink? Is this a guest bath or the only bath? What‘s on wall opposite sink - a towel bar maybe? Decor is my last question & I think the easiest part of dealing with that bathroom. 😁. For that, work with grays, from counter & floor & blue (?) from the odd design in the shower. For the rest, it depends on who will be using this room. Can you show with a pic how that over sink cabinet opens? Looks like left narrow door will hit hand towel bar. Maybe a mirror could be hing on wall above that towel bar so one could see themself while standing at sink

I say pick a bold color for the walls. A deep steel gray or if you are adventurous with color, a green or a red.

And replace the overhead light maybe with a track light fixture if you can find one for bathroom use.

@KW, there are shelves in the alcove. The cabinet does not have a mirror, and the only thing across the sink is white wall.

I like the ideas: shower curtain, steel gray walls, mirror over the towel bar. I’ll post updates and ask for more advice, especially on what to do with the space under the sink.

This is the guest bath. Same issues.

You just need to add color and drama. I would add a dramatic shower curtain. The tiles can peek out at the top. Add artwork and a black vase with white floral. Add multi color blue towels. A soap dish.

Laural Home Blue Orchid X-Ray Flowers Shower Curtain · More Info

Polystone Vase W-Inlay 20"H, 9"W 48861 · More Info

Polished Marble Jet Black and Alabaster Soap Dish - Natural Stone Luxury · More Info

@LB, great suggestions. I’ll get right on it!

Thank you! Some inspiration to get you started.

If you have space, how about a candle holder?

Little Girl Mermaid Votive Holder 6.5 Inches · More Info

@Tahia Lorenzo - you said this is rental - are you allowed to paint? I think you need a place to hang bath towels. 3M Command hooks come in some pretty big & sturdy sizes with silver finishes. A couple of those on long wall by shower would work for towels. I noted all the shower curtain suggestions. I’m not a fan of that one because I think it takes away space. But, maybe you do everything else - a rug, nice art on wall & over toilet - or a mirror over toilet & then See if you feel you need to hide the tile. For under sink counter - I’d look for a cart on wheels to hold makeup, toiletries, TP etc. Handy to pull out when need stuff. At least you have great storage shelving in that alcove!

To brighten the flooring, I would also add a 3' x 5' area rug, if this size fits. Inspiration for you. Keep it light.

Safavieh Dip Dye Collection DDY211 Rug, Blue/Ivory, 3'x5' · More Info

Traditional Persian Vintage Rug, Blue, 3'x5' · More Info

It's odd that there is no mirror on the cabinet. Use a stick on hook to mount.

Or double sided velcro squares.

https://www.amazon.com/Home-Basics-DM47052-White-Mirror/dp/B01IF3RWK4/ref=asc_df_B01IF3RWK4/?tag=hyprod-20&linkCode=df0&hvadid=312142336543&hvpos=&hvnetw=g&hvrand=9172839811338714306&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9031163&hvtargid=pla-579544676798&psc=1#

To repeat the oak cabinet color, here is an inexpensive way to add art above the toilet.

Purchase a larger black open frame (approx. 16" x 24") & oak open frame at thrift stores, close in size, to fit inside each other.

Print out a greeting card photo or internet photo, glue mount on a harder backing.

Photo can be small.

Velcro double stick mount.

If you need storage inside this bath?

* lidded basket below sink