When I've worked med-surg, and been on my feet alot at work, I've always
worn "full support" pantyhose (under my uniform pants), and it makes a big difference by the end of the day. I started that in nursing school
many years ago, and liked the results so much that, since then, I've worn only support hose even for everyday use outside of work (when I wear pantyhose or knee highs). I only buy support hose -- not only are they comfortable, but they're sturdier and harder to run than regular hose, so they last longer (which, to me, makes up for them being a little more expensive).
Hanes makes "active support" panty hose that you can buy in bulk through their outlets at a good price, and that's what I've always used -- they come in white and some regular colors. For everyday use, I like their "sheer energy" hose (also available in bulk through the outlets) -- not quite as much support, but sheerer and better looking for regular wear and they come in a wider range of colors.