How about a Rainbow Mesh overlaid with circles of varying transparency? It has vibrancy, lots of colour as juicy as you like, and offers a refreshing antidote to the grey feel of last year. You can work this up to fit in with loads of design applications. Colour yourself happy 🙂
It looks like it’s a lot of work but it’s really easy to create and edit. I’ve written up a pdf tutorial for you here:
No More Mondays 