Book design ideas

I've had a few idea about how I want my book to look, I know I don't want a massive book, I think I'm heading towards a standard landscape. My first idea is to have to book hold child-like characteristics as this is what I'm kind of promoting in a way, I could use lots of bright, bold colours, big writing and a smallish size. Erwin Wurms book 'The artist who swallowed the world' influenced me to get this idea, I like the cushioned front and back cover and the bright pink with contrasting green colouring.

Another Idea I have is to go the opposite of the first idea and actually make the book like more sophisticated. The risk with going against my first book design idea is that the second one may look boring and dull whereas I know the first one would be much more eye catching. This idea does have its positives though, the plain, bold and tidy finish would resemble that of 'what we're more like after losing our child-like characteistcs.' The book would itself show a loss in child like characteristics.

My third idea is to start the book off with the first idea and have the last few pages and the back cover as the second idea to show the change in loss of characteristics as you read on but the problem with this is it would be very very perculier, I'd want people to take my book seriously and this idea as well as the first one might not allow people to do so.