I'm 28, and here's what I've noticed about my skin after losing over 50 lbs.:
The skin that's shrunk on my thighs, arms, breasts, hips, etc. has been thankfully quite elastic. I still see the old faded-out stretch marks (most of them are white now) but there's no weird saggy skin. These are probably also the areas where I've built the most muscle, and I think that's likely correlated.
On my belly, I do have some excess skin that's sitting right above my belly button. I can feel that there's still some belly fat in there, but there's also a bit of loose skin. My mother says it looks similar to the skin a woman has on her stomach after she's had a baby (I said "Yeah, my fat baby!"). It's being more stubborn than the rest of my body - but I imagine that if/when I spend more time on my abdominal muscles, that might ease the little stubborn roll that's there. I still have about 25 lbs. more I want to lose, too. I've also heard that the belly fat in general is the most stubborn, as is the belly skin.
I also will second skin lotion with Q10 and/or Vitamin E. It can't hurt.
Female, 28 years old, 5'4 1/2" tall
Starting weight 1/4/11 = 215.2 lbs.
Weight 9/3/12 = 164.9 (net: -50.3 lbs.)
Current mini-goal: 160 lbs.
Next mini-goal: 150.2 lbs. <--- Official "Healthy BMI" weight
Estimated final goal: 130 lbs.
"You don't have to change your life today. You only need to change your day today."