I've just looked again at the first one you posted op, and changed my mind a bit - it's not as dreary as I thought!
I think the problem, though, is the idea of a playroom area with what seems like very 'grown-up' understated colours and designs. I get that you don't want primary colours, but could you go for a different colour on that wall? For example, if the rest of the room is painted in a stone colour go for a soft teal for the playroom wall? Just a thought.
(Doesn't have to be teal, obviously! Farrow and Ball website might give some inspiration).