Ok, this is a great space so easy to fix. People might give you specific advice but really it depends on your taste. There are 3 important things you are lacking that will fix your room - zoning, texture and lighting. zoning - if you can walk into a room and read it immediately it translate as boring. To fix this you need to draw the eye around the room. You can use furniture, art, points of interest to do this. Perhaps a cool chair outside the bathroom door or a chaise lounge. Perhaps a big banana plant or fiddle fig between your windows. Perhaps a huge piece of art above the bed. Perhaps some cool wallpaper art there (check out Curious Egg). A reading nook? How about filling that massive space between the end of your bed and wardrobes? You could put a huge pouffe, love seat or ottoman on a rug there so it looks a bit like a dressing room area with seating. Anthropologie do some great options. texture - you need a huge rug to go partially under your bed and soften the room. Try French connection home or la redoute for affordable options. Why not texturise the wall your bed is against. Do the whole wall or a textured headboard made of timber etc. Abigail ahern does some great, easy to assemble faux wall options. Again I would recommend plants. Not everyone likes these I need a bedroom but again Abigail ahern does some great fauxs. lighting - the room is very light and bright but at night it probably can look a bit stark or cold. I would definitely advocate some free standing lights. These should be near whatever zones you create. Certainly I would have some bedside lamps and maybe a taller freestanding lamp elsewhere. Rule of thumb in a room this size is at least 5 lamps or freestanding lighting units! finally, if you like neutrals and want to avoid colour, neutral colour through texture is a great solution. A beni oudain rug, a large sheepskin over the bottom of the bed, a large wicker chair. And of course, plants. good luck!

regarding guests above the main bedroom, I respectfully disagree; I think bedrooms should be kept private, certainly not joined to a guest's bedroom we do need dimensions to proceed though what if you fitted the office above and closed it off, perhaps with a retractable screen, so you wouldn't disturb the person sleeping. the downside is that you are combining work and relaxation into one area, so it's not the best solution. which means... if there's not enough space above, and I do doubt that there is, rather get a wall of closets in the bedroom, and change there. It would also save the inconvenience of stairs; think of times you forget items and have to go up and down repeatedly, times you're deciding what to pick out and need space to arrange clothing options, times you're packing closets, or exhausted after a long day out, the option of a mezzanine dressing room loses some appeal to me. Another option though, is to have closets in the bedroom for daily clothes of the season, and some above for other seasonal and occasional clothing

I'm not against it, it just depends what else is in the room etc and would repeat a little elsewhere to get the right balance as Jonathan said. I've just picked a few DG rooms (love their room sets!) but google more images to see what you think. These are all against light backgrounds but could look equally good on dark. I know in theory you "should" avoid vibrant colours in the bedroom but tbh you can't see them in the dark!

I recommend it like this, The current vanity on WIC is on the way of the walking path so Its better to relocate it and place it on the outer wall, this way the lady Will not get disturbed when applying make up when there is passerby, There's no need to have huge window on WIC so instead use smaller window for natural light on each side of vanity, also theres no need to create massive walk space better maximize wardrobe storage as people tend to spend little amount of time in WIC Don't place the headboard of the bed alongside the door directly,it Will be uncomfortable for the people who Will sleeping there, I know some sacrifice it to have a view directly to the window but for long term it Will cause restless of sleep For the small lounge its better to not place a desk facing against walkway, people Will get stratled easier if someone coming from your back, with this layout you can put bookshelf and have conversation with the person on the armchair. The desk also closer to the natural source of light For the ensuite the jutted out pillar Will make it little bit odd so I suggest to level it and place the sink in this area instead of toilet the reason is just when you relaxing in the tub you wont want to be too close to freshly used toilet