Looks like you may already have a little bit of color blocking going on, but I'd increase the contrast between the shades of paint. Do you have access to the original paint chip card? Paint two of the walls in question in two different shades from that same card. Consult with the paint source for the complimentary color to accent the third wall. I think the middle wall to the right of the stairs would be the one I'd accent. Then add a large piece of colorful abstract art to that wall. Here's a quick tutorial on color blocking. https://www.houzz.com/magazine/building-with-blocks-of-color-stsetivw-vs~639

I agree too! I personally love chalkboards as they add a fun element to the space. Also a quick tip- Use a soft cloth dipped in a mixture of warm water some vinegar to clean a really messy chalkboard!

Ka_kamakshy interior architect , Did you check with your contractor why he thinks it will fall down. May be he hasn't done it earlier or he doesnt want to do it. It is very much feasible to clad the walls with marble/granite/ other finishes.

Thanks for both of your responses CUBSpaces team and Shweta from Shades studio. It really gives a clarity about possible consequences. I am now doubt free about changing whole things in Bathroom as it will be interconnected. However will appreciate your opinion on few things: 1. Kitchen wall tiles: I have those from countertop height to roof(almost area of 6X15 feet) which are good and not hollow. I changed countertop 5 years back without any damage to these tiles. It might cost me another 10-15 K, but I feel the whole process and quantity of wasting old good tiles makes me little sad. 2. kitchen countertop: Made new around 5 years back. I don't expect to get it all intact. But large pieces can be cut and can be used as top for other freestanding structures like dishwasher, front load washer, heighten base cabinets, etc. 3. Plywood: I don't mind giving enough labour charges for old sheets recycle. I am planning to use doors, loose sheets(like kept on bed frame of settee frame.) or parts of big frames like settee. I am keen on reducing waste than to save money. You can see various DIY ideas by western people, who remove or sand laminates and re-paint furniture, or carefully remove hollow tiles and re-attach them. Some are also re-painting ceramic tiles. I am just asking myself: Are we creating more and more waste by use and throw approach every 10-15 years, just because we can afford it?