i agree...
i dress for the environment, as well as for myself.
i'm in grad school, so for classes- juicy suit, tencel/modal (my favorite fabric for dresses) dresses w/ flats [juicy, j.crew], or a simple top and slim rinsed (i can only wear rinsed or black jeans...anything lighter than dark dark blue or black makes me gag) jeans w/ flats/sneakers [juicy, vans, converse].
for meeting with editors- pretty much whatever i want as long as it is chic...if i'm wearing something kooky, i do simple clean makeup and my hair pulled back into a low ponytail or tight bun.
for running errands/around the house- same as i wear to classes.
going out- vintage dresses (which i collect while traveling) with my louboutin ankle boots, rochas pumps or any pair of pedro garcia pumps. i detest a cutesy "going out" top/jeans/heels to go out, but that's just me. it does look precious on tons of girls.
brunch/dinners/movies with friends- dress/flats, vintage top (i'm addicted to vintage blouson tops)/jeans/stacked heel, vintage top or boatneck top w/ slim, ankle length pants/flats.
i have a ton of clothes, so i never have an issue deciding what to wear. i have a solid arsenal of dresses that i can wear a zillion different ways (dresses are easiest, imho...you can change the entire look with just a bag/shoes). i also buy things that fit me well and simply buy what i like. i never look to magazines to inspire what i wear because they just cloud your thought process, imho.
have fun with your wardrobe...don't focus on trends OR classics. simply buy what is flattering and what makes you feel good.
people tend to get hung up on classics, imho...while you shouldn't go out looking like a skank (lol!), you should look modern. you can bother with the perfect white shirt and black trousers when you're 50 and nothing else looks good on you (NO OFFENSE TO ANYONE OF THAT AGE).