I like Gap's new store, Forth & Towne. They're stylish, but not trendy. But they're pricey. Like Banana Republic and up prices. Geared towards women in their 30's and up, I think. But I like it even though I'm 23.
Target has some nice stuff that kinda skirts the stylish/trendy border. They've got good basics, though. And they're prices are good. I don't have a WalMart near me, but I've seen some commercials and it looks like their new women's clothing line is similar to Target's. And Kohl's is supposed to be good like that, too.
H&M is a bit on the trendy stuff, but the prices are good.
You know the show "What Not to Wear" on TLC? It was originally a British show, and the British hosts wrote a book called What Not to Wear. I haven't looked through it too much, but if it's like the show, it's got tips to make sure you dress to accentuate your features and stuff like that. B&N has it in the Health section, with the makeup books and stuff like that. They're also a Lucky's Guide to Shopping (or something like that.) I've flipped through this one, and while some of it's basic wardrobe "requirements" are excessive, it has good tips and explains, for instance, why you should have a blazer, and what you can wear it with for which occasions. That's in the same section as "What Not to Wear."
I personally wear a lot of sweaters over t-shirts or camis or button down shirts. Cardigans are good, too, especially if temperature is an issue. Add pants or a skirt or jeans, and boots or sandals or sneakers, and voila! Instant outfit. And since I can change the dressiness of my outfits by wearing jeans or black pants, my weekend wardrobe is similar to my work wardrobe.
The best thing to do might be to walk around in different stores (mall would be great for this) and get an idea of what people are wearing and just look and see which stores look heinous to you and which you might want to come back to. Don't buy, just look, maybe try things on, if you want to get an idea of which styles would be flattering. (I have big hips, big boobs, and a small waist, so I tend to stay away from high-waisted, flowy shirts because I think they make me look fat. I want to accentuate my curves, not hide them behind a shirt.) Flattering clothes make you look better dressed than pricey clothes that are "in" but don't do anything for you.