In case anyone remembers my post, I finally found petite loungewear in a big range of colors and styles, from Old Navy of all places! I'm thrilled because I don't like to spend a lot on these items as mine tend to take a beating and wear out quickly. They don't have it in stores so I have to guess on size, but at least I can return it to stores.
They also carry their yoga line in petites - yay Old Navy!
Per Angie's suggestion, I did try J. Crew's lounge pants, which were great, but I really hate to have to spend $68 on lounge pants, plus $10 or $15 to hem them.