A small bathroom is the fact of life for most people – even if its an en suite. How do you deal with the lack of space. Frankly if its a second bathroom I’d lose the bath – they take up a lot of room – if you restrict an en suite to a small basin, WC and a shower – you can have an en suite in a smaller area than many walk-in closets. The trick is to making the whole room a wet room and maybe having a changing area in you adjacent walk in closet.
Other old but good tricks is keeping the bathroom in white or very light colours, paying attention to good lighting and strategic use of mirrors (make sure they are heated so you can actually use them too!) Ventilation is also very important in a small bathroom if you don’t want to be cleaning up the mold every few months!