Thanks all. Lynn - I started training my legs 1x week heavy with a trainer about 8 months ago, and yes I am very happy with the results I'm getting - BUT those results are SLOW and come from total consistency - on the heavy weights, the uber clean diet, and the right amount of cardio. My legs are big and I'm sure I will never be happy with them. But my trainer (who has the same build) says that year after year, by staying true to the program, she sees results. I do what I call ATG, or a$$ to ground squats - with about 165 lbs. and my least favorite, but indeed most effective walking lunges: 4 sets of 25 with a 95-lb barbell, etc. I can do the full leg extension, but my trainer has me do a few full, then the partials, coming down half way and then back up with the hold you mentioned.
I'm training for a figure comp and would LOVE to see those 4 distinct parts of the quad. "The elusive quad!" Thanks again.
ETA: Jacque - you're right on the feet closer together. We use the Smith Machine with my feet way in front of my hips, and only about 8 inches apart, squat down to the ground and then push up. I totally feel it in my quads, so I know I'm doing it right, just...want...to...see...more.