I think all of them seem to have the same mood so any of those colour choices would suffice.
I am glad you've added more streaks to the sky. Having just the one would mean that either it's miles behind them in the distance or up close and really small. Adding more of them implies that they're looking at the whole sky and that works a little better.
Valence: Thank you, glad to hear the changes made were for the best!DigitalDave: Thanks, much appreciated! .............. I resumed work on the image and it's come quite some ways. Pretty happy with how it's shaping up, although I want to push the image as far as it can go in terms of refinement and detail. Below is the current progress:
I know you're not done yet, but currently the one thing that sticks out to me is their skin tone - it would benefit from being warmer (more pink, I think with your chosen colour scheme). They look a bit greyish at the moment.
Any an all misspellings are henceforth blamed on the cats.