I have shorter thicker legs, and I like a dark wash bootcut with a fairly high rise. Those seem to be the ones that visually lengthen me.

I definitely fit this description, and have found that a darker, flatter wash and a higher rise work best. As for cut, all styles can work (at least for me) as long as those other two factors are right. I wear skinnies and straight-legs most often, but find that my wider, trouser-cut jeans actually lengthen me the most (though I do have them hemmed for very high heels, which helps).

Pants: Dark wash, straight or bootcut with a dark shoe (to create a long line).
Skirts: Knee lenght, opaque dark tights and shoes of the same color of the tights
or
Knee lenght, nude tights and nude shoes

Always think in creating a long vertical line.