SFGate

ASVInteriors What a gorgeous idea. Just love it! I would leave the outside this colour because it is sophisticated and in the end, kids do like "grown up" things. On this inside don't go for pinks, but a lilac will contrast with your pumpkin(?) wall colour and still work with in their "home".
Flooring - I suggest cork flooring: search cork on Houzz.. We have a number of cork people who can give you loads of pros and cons and it is soft, easy to maintain and comes in lovely warm colours.

PYRAMID DESIGN GROUP Prefinished wood floor with colorful and playful area rug .

PYRAMID DESIGN GROUP Prefinished wood floor if dampness is not a problem.. if dampness/moisture is a problem go for ceramic tile with a synthetic indoor/outdoor area rug.