Hi - I like the royal blue or the powder blue with bright yellow or you could have a mix of both the royal blue and powder blue. i.e. if the blue is for the walls - then one feature wall in Royal blue would look nice and the rest of the walls in powder blue. If you bedding is yellow and then you could also use a bed runner on the yellow bedding in either the royal blue or the powder blue - the same goes for a rug if you need a rug. Also, if your bedding is yellow you can also add some bed cushions say, two in royal blue and one in powder blue or vice versa. So, for me I would definite say both the royal blue and the powder blue with the yellow - this would give you lots of depth and also the 'POP' with the yellow.
Have a look at these pictures to see how well the blues go with the yellow ):
https://www.google.co.uk/search?q=royal+...
Hope the above helps :)
Powder blue
Which one is better and will it go with black and white horizontal stripe or bright yellow?