My well-worn beauty book states that more mature eyelids look best with matte-finished eyeshadows. Applying a light-colored shadow near the lash line and a deeper shade in the arc above the crease where most eyelids begin to sag is a good rule of thumb for more mature skin. The lighter shade makes the bottom of the lid more visible, while the darker shade makes the puffy top part recede giving you a wide-eyed, more youthful look. Also, when using an eyeliner only outline the outer half of the upper and lower lids to "open up" your eyes. Urban Decay and Smashbox both make great matte eyeshadows that are highly pigmented and come in a variety of shades.
I hope this info is helpful to you.