I really enjoyed reading _Style is Not a Size_ by Hara Estroff Marano ($2 used on Amazon.com) for some guidance on flattering cuts and fabrics, and check out the _Color Me Beautiful_ series if you're interested in suggestions on clothing colors that work with skin tone and hair color.
The most flattering clothes in my closet are salwar kameez suits. I own ten of them! A salwar kameez is a three-piece outfit: the kameez is a tunic that falls somewhere in the range between right above the knee to mid-calf; the salwar is a pair of drawstring yoked pants that come to gathered cuffs at the ankle; and the dupatta (also called a chunni) is a six-foot scarf you wear around your neck or head. Although often Muslim women from India and Pakistan wear salwar kameez, you would not offend any religious or cultural sensitivities if you don't fit that demographic.
You can buy a salwar kameez stitched to order on eBay (search for "salwar kameez any size"). That way, you can tell them your measurements and get a custom piece. And we all know, it is body-skimming good FIT that is the most flattering in clothing. You order the fabric, and then most of the companies will let you choose the cut of the neckline and the cut of the sleeves, and you can choose either loose-fitting salwar or tighter-fitting churidar pants or western-fitting parallel pants. If you're more adventurous in your taste in colors and patterns, you can get custom-stitched sets dirt cheap at Priyanka's (
http://www.designersoutfit.com/salesuit.php3), a company that caters to women of Indian descent living in the West.
It might feel odd the first time you wear a salwar kameez in public if you didn't grow up wearing them, but I've gotten nothing but compliments, compliments, compliments. You get noticed, but you are also modestly covered. And the clothes are light and comfortable -- sort of like working in your pajamas all day.
Oh, I should mention that I don't own stock in any salwar kameez companies, just a happy customer who feels like she looks good in these outfits no matter what the scale happens to say that year.
Geri