I work in a small office with a very casual environment. Today I'm wearing denim shorts with a casual summer cotton blouse. If I have a meeting with a client I'll "dress up" to business casual, but these days most of our client work is by phone or email.
I know what a previous poster means about "missing" dressing up, though. Most of the time I'm perfectly happy to stay casual, and of course there's nothing stopping me from ratching things up a notch ... but every once in a while I look at my skirts and dresses and even a couple of suits and miss wearing them more regularly.
Although I do not miss pantyhose! Not at all, ever.
I get my dressier clothes into use when I can, though -- I have season's tickets to a couple of theatre companies, on weekday nights, and I go straight from work. I know theatre is another place where the dress code has relaxed over the years, but I figure if I don't dress up for my theatre dates I'll never get to wear that stuff!