With the earth-toned tile floors, it would be nice to add some green to the bathroom but keep it light. How about Anatolian paint from Magnolia Homes - similar vibe to your guest room?

I agree with green, a lighter shade from the same color strip.

Maybe find a fun rug or shower curtain that incorporates the color of your floors and vanity. You could paint the walls a color that is in the print, or paint them white. White would allow you to change the color scheme through accessories!

I am not a designer. I have a similar delima, though my bathrooms are worse. Beth H made some great suggestions. You can see them on my post.

I have learned a lot from reading other design delimas. That's why I suggested the rug/shower curtain. I think something like this would be nice:
https://www.anthropologie.com/shop/bea-rug?color=089&size=2’ X 3’&inventoryCountry=US&countryCode=US&gclid=CjwKCAiAz4b_BRBbEiwA5XlVVp8HCNuoGvAb3xg0LyqQ-s4waPwBHcxBa4CrPdxX-IGksQsLd9q0KBoCq4wQAvD_BwE&gclsrc=aw.ds&type=STANDARD&quantity=1

If you like blues, why paint - as said, new curtain, new light?

these come in window curtains too. The pleats give the shower curtain a more textured look

Linen Button Shower Curtain Linen, 72"x72" · More Info

Sylvie Fox 18x24, Gray Framed Canvas Wall Art by Simon Te Tai · More Info

Blue, grey, etc..

https://www.kohls.com/product/prd-4150474/lush-decor-linen-button-shower-curtain.jsp?skuid=61431043&ci_mcc=ci&utm_campaign=EC%20DECORATIVE%20BATH&utm_medium=CSE&utm_source=bing&CID=shopping20&utm_campaignid=380493021&utm_adgroupid=1228154695363651&gclid=cea50081109a1be746c55f63ac9661ec&gclsrc=3p.ds&msclkid=cea50081109a1be746c55f63ac9661ec

Bedroom isn't fully rustic at all -- so, here's quite ruffled, called 'farmhouse' -beige to go with floor / a striking vanity light then / curtain in white -

https://www.amazon.com/dp/B08HBQ1XJN/ref=sspa_dk_detail_1?smid=AISYMB8I6OC5P&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFNNE5VRU9FRDM5VVQmZW5jcnlwdGVkSWQ9QTAzMTQyODkzVFpVV1YxTUs3MlNaJmVuY3J5cHRlZEFkSWQ9QTA2MzYyMzgxNUxJOTRFTEFKUldWJndpZGdldE5hbWU9c3BfZGV0YWlsMiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1 ------------

22.6W x 6.3 x 8"H / glam transitional features pattern of K9 glass crystal accents.

Progress Carlyn Collection 3-Light Bath Vanity P300102-020, Antique Bronze · More Info

the blue is actually very nice. the tile, not so much.

Paint the vanity white or navy, get a new countertop/sink combo and a nice patterned rug to hide most of that tile.

You can also paint the tile if you like.

frame out the mirror w/trim molding if you like. shown here:

hang more colorful art or shelving above toilet.

basically same blues. (the tile and the dark vanity are the problems in the bathroom, not the wall color) painting the walls a gray, or beige or any other neural, isn't going to do anything amazing.

here are similar blue wall colors to show you what vanity color and floors do

you can buy a new countertop w/a sink for less than 500.

paint your floor tiles (online how to's)

similar blue walls and decor ideas

if you want a full remodel:

everdebz,,,I like that mirror!! but I could make it like that for less than $30!

raw wood like Fir, cut to fit the mirror, (HD will cut it) and do a blue aniline dye or dark blue stain. or even a cobalt milk paint. lot cheaper than the $200+ price tag it has!

(but her vanity is 48" I believe.

Toasty curtain and animal art I think you clicked 'like' - soft combo with pale blue paint..

Over toilet hang small canvas which I find easy to wipe -- then anything you find/like to increase height... over.

Sylvie Baby Giraffe Animal Print Framed Canvas Art by Amy Peterson, 18x24 · More Info

Plain curtain to use interesting hooks.

Barnes Mill Collection 3-Light Bath and Vanity, Antique Bronze · More Info

"Lauren" Dobby Fabric Shower Curtain in Sage · More Info

20 W x 9 H

Rustic Three Light Bath Vanity - Exposed Bulb Clear Cylinder Shades · More Info

Back Plate Weathered Zinc Finish with Clear Glass / a modern farmhouse appeal with a rustic design of oversized "rivets" and genuine pipe fittings. The clear glass and washed wood, with a weathered zinc finish add to its urban look.

Beth, before I read your post, true, I deleted the bright blue mirror seemed so bright ... in another color, you would!! she could!?

yes, she could. not difficult.

and the corners weren't even miter cut. they were butt joined. even easier to install.

I like the giraffe pic w/the blue too. ties in the brown tiles.

I really like that light blue paint on the bathroom walls.

And it would look just dreamy with white cabinets.

And if you could swing it, a floor porcelain tile that looks like marble.

I like that deep green in the bedroom, it reads as restful to me.

You could do a few things in there to make it a better room for guests, though.

I would get larger bedside tables, and have them have drawers.

People want to be able to put away their phones, wallet, eyeglasses, jewelry, etc, and do need more than one drawer.

The one bedside lamp you have is too short.

You can avoid that whole problem by getting two wall mounted lamps that plug into sockets, so you don't have to call the electrician. They even have the type that adjust up and down, so they will accommodate a tall guest on one side and a shorter one on the other.

Some art work is a good idea too, and a colorful throw for the end of the bed.

I am not one for those decorative pillows, they are just work for your guest to have to figure out where to put when they go to bed.

What you could do is get some large Europillows (26" x 26") , 2 or 3 depending on the width of the bed and put them closest to the bed, so if your guests are sitting up in bed reading they can prop themselves up against them. You can get all white shams, or get colored shams that coordinate with your paint color and decorative throw.