here's another picture

Even simpler, I think you could get away with painting the vanities white (forgive me for not doing so), changing your rug to a bigger, fluffy white one (size as below), and adding a couple of cheerful pieces of art -- I like this octopus and he/she picks up the blue in the frieze of tiles around the bath (which it could be a bit expensive to change -- and certainly a bother). And I think the pics on each side could be identical, as long as there's a sense of humour involved. If you want them reversed, as I have done, I'm sure many suppliers could organise that for you. Or you could find an image with no copyright complications and just organise it yourself, using our digital world of wonders. But do pick up the blue. If you can't chip it out, flaunt it.

https://www.etsy.com/listing/128109138/offset-octopus-nautical-art-print-sea?ref=market

Here's some Original Artwork for your Bathroom....Will add more color and life to your wall and enhance the look....for more Artwork check my shop too...

https://www.etsy.com/shop/PooArtGallery?ref=profile_shopname

I agree with everyone paint, it is the cheapest way to make a change. I can't see all the colors in the band of decorative tile around your tub, but pick your colors from it. If you don't use the darker color on the wall consider painting your cabinets that color.
The window above the tub is it first thing you see, so decorate it. There are plenty of DIY for curtains on the net look at these, or shop Goodwill.
Find something unique, tall, maybe it can be used for storage for each of the vanities.

I'd be tempted to put a red (or color of your choice) runner up to the bathtub, with coordinating towels. Replace the blinds with light, translucent drapes (you can probably get these at IKEA on the cheap). If you're good with plants, get a staghorn fern for the wall.

This bath could use a little drama.