For each bathroom choose a neutral color that U see in the tile Here is how to find the perfect wall paint "match" http://www.lindaholtinteriors.com/2011/07/testing-wall-color-101/

You could add colourful accessories and Shower curtains. Also, you can stickers/ decals in dry certain areas.

Thanks Shwetha for the response. But it's not about exhaust fans.. I want to cover the glass with removable mesh.. is it possible on UPVC

You are in tight spot in terms of dimensions of the Guest bedroom, there is not much flexibility except for the pantry outside room which can have an additional wash basin as suggested by Nitin from corner stone above. Although, since its guest bedroom, TV viewing might not be priority unless you are looking to use it as your entertainment room for family. If you are planning to use it as entertainment room, then, instead of full fledged wardrobe you can have long wardrobe wall unit upto 2'-9" height for storage & TV/entertainment arrangement & play around the space above. In this case, you need to shift electrical & cable points to wall marked for wardrobe.