I'm a massage therapist, and long ago (I've been practicing for almost 16 years) I knew that I needed to look professional while still meeting the movement and comfort needs of my work.
I wear active wear pants in black or dark grey (long in the winter, cropped in the summer). I use Lands' End because they don't pill, wear through, fade, or stretch out, and they're not too tight. They either have a bootcut or fuller leg so as not to be leggings. For tops I wear Eddie Bauer solid color t-shirts in 3/4 sleeve (fall/winter -- I push the sleeves up anyway) or short sleeve (summer). No logos or prints. Crewnecks are horrid on me, but I have to have a few for some work I do that requires me to bend forward a lot, otherwise I do scoop or v-neck (not too low). The shirts fit close to my body so they don't get in the way, but they're not tight. I also wear Birkenstocks in my practice, as I need the support being on my feet all day. And no jewelry (rings and bracelets for obvious reasons, but nothing else, either). It may not be terribly stylish, but my work is not about me or my fashion sense -- it's purely about my clients -- and my clothes are about projecting a professional image within a very casual atmosphere. I can move comfortably, and everything is inexpensive so it can be replaced easily.
Some MTs wear scrubs (certainly a professional look, though I tried them once and couldn't move in them), and many others push the boundaries of what I would consider professional (and even appropriate -- but not in my office!) so I have a little different situation when it comes to de-casualization.
The only drawback is that I overcompensate with buying for my non-work wardrobe since I have no variety in my work wardrobe! But I wouldn't have it any other way.
