What about a dark brown? I think that grey would look too 80's. i would also replace your mirror with a larger, simple one. Fluffy white towels. Good luck in selling!

Or a simple tile over the countertop.

A simple pedestal sink- would be a great option.
A mirror hung lower and in an oval shape with a simple frame- or mirror on mirror frame would be nice.
A single faucet without handles is more appreciated, in any bathroom.
Colour- if you change out the cabinetry and sink and the ped is white, as is the toilet- the only real dictator would be the flooring.

If you are steadfast on not replacing the cabinetry etc.
Peri winkle, navy blue or teal- think Arizona colours or Italy. The ochre is not doing it. Ensure that your towels are patterned to comply and your soap dispensers are hidden. The faucet set is quite visually demanding.

Great art- and you are off to a great sale!

is it as pink as the picture? it looks like the same color as that old pink tile you sometimes find in older houses.

if it is, i'd go for a vintage look and play it up. do white walls and black high gloss accents.

if it's a light terra cotta, do pale blues and yellows. it'll look like a faded hacienda style.

If you are selling your home, most buyers are interested in bathroom and kitchen condition. If possible, I agree that putting in a simple pedestal sink, keeping your faucets, and paint. If $$ is a big consideration, do the wall paint and change the mirror as suggested. Cleanliness throughout the house too.

The counter top looks more pink than terracotta. I would stick to crisp white walls and towels. If you try to match that colour it will only bring it out more. The white will make your bathroom look clean, fresh and neutral and buyers won't notice the counter top as much. The mirror is too small. A bigger, round mirror will make the space look bigger and distract buyers from the countertop.

Will you be replacing the mirror? If not, choose an off white to go with the lightest glass in the mirror edge. If you choose a color that contrasts with the terracotta, it will make the terracotta "pop" or stand out more.

Do you have more photos showing the vanity?

Some paint will stick to Formica with appropriate prep. You might be able to paint the vanity top white to match the sink.

Thanks for all the comments! Yes, the entire powder room is very dated, and small...

I really like the idea of the pedestal sink and oval mirror- and bringing whites in. Thank you all so much!