I like the rendering of the building. It definitely needs to be color like #3, but more green. But it still needs the other elements (rainbow, hot air balloon, more yellow brick road). I like the perspective of the Y.B. road, but may need to see more of it.
Overall it needs a sense of feeling magical (e.g. small sparkles/stars may help with that idea).
I like your subtle use of color. I'd like to see other ways of possibly showing more rainbow. (and if it is possible to get the hot air ballon integrated.).