from overcast to bright sun

When I shoot in this kind of light I simply let the background blow out. Its not important and still is recognizable even if overexposed. In the future you can add more fill light if you want it balanced.

Something like this?

Quick and dirty but used the the camera raw filter (better to use Camera Raw if you have the raw image) to lower brightness and change colour temperature of the background. Pro-Digital's Star Filter pro for highlight stars.

Dave

The yellows in the background can easily be shifted into desaturated greens to make things darker. Even a simple Hue/ Saturation without any additional masking does a good job at that, though of course, for the final result you may want to do just that to not muddy up the models. Boosting the lights will be near impossible, though, unless you intend to work your fingers off. This is a case whre simply placing some lens flares or another graphic on top that gives you the glittery effect would be much, much easier.

Mylenium