I would have to say, it is not, a no no. However, how you decide to do this will determine whether it is positive or negative. If the toilet is in direct view as you enter it is likely to be negative, but the impact can be reduced with a smaller pan and an in-wall cistern. Noise and smell are often factors that will influence the decision. So, the smell can be overcome with an automated odor extraction system and there are also low noise inlet valves available. As far as property value is concerned there is a multitude of scenarios and just as many opinions, so consider how much convenience this will give you and how long you intend to stay in the property? perhaps it may be better enjoy your home the way you would like it to be.

I have a shower over bath combo' which its plastic resin something? It's a old bungalow and pitifully small. The amount of times I have nearly slipped over getting out, or lost my balance with soap in my eyes/ or after having a glass of wine. hate hate it. I did see a shower room with a additional hand held device and a over head shower. I thought that good for the odd squirt your feet down. The next owners will probably rip it all out and start again any way when design ideas change.

How big are the floor tiles? It may look unbalanced with a more delicate tile in the floor and the 600x300 on the wall. Are you able to continue the flooring tile up at least one wall for cohesiveness.

I would prefer to keep the WC separate to the Bathroom as you have 3-4 kids? who will get bigger very quickly, having a powder room downstairs won't help with the morning rush to school., But it's your house so I have added a pocket door between the WC and Bathroom. I have also taken that small robe space for an extra vanity in the WC/Powder room. No width dimesion given for the WC The ensuite could use that extra entrance space as a sit down makeup and hair bench for your wife.