What is the dimension of your bathroom? Looks like 4 feet wide, can't make out on length though. Glass partition or tiles partition for shower would help to keep your bathroom clean and dry and revamp look drastically. Wall hung WC is must, again from cleaning and look perspective. If window is not providing any light ( though your photo suggests some light coming from window) this area can also be used for multipurpose. You are welcome for more queries. Tiles selection can be decided based on a theme as well.

I disagree with the advice above, the bathroom door that is in the passage should be closed. The reason for this is that you already have a bedroom without an attached bathroom. If you go by the advice above you will then have two bedrooms without an attached bathroom. Its not ideal. Also, you havent told us for which uses are the other two bedrooms. Are there going to be old parents in the bedroom with the bathroom or kids or are you going to use this as a guest bedroom? If you close the door in the passage you can have a bigger vanity by moving the WC behind the door that is from the bedroom side. This is also good because you should never have a bathroom door with a view of the WC. The WC is a very private spot and there shouldnt be a direct view of it from the room. Also we tend to spend more time sitting on the potty than washing hands, looking at ourselves or taking a bath. Once you move the WC you can have the vanity extending till the wall and will be 2.5x bigger than what you currently have.

hi, you can select from 'Noken' brand designed by renowned Architect Norman Foster... they do really have high quality vanity.

hi u can try taking full length mirror which matches with counter length