in the past, i have neglected layering my bottom half when the weather gets chilly. luckily, leg warmers add the warmth when you're outdoors and are easy to remove once you are warmed up (read: virtually hassle-free compared to double layering pants).
sockdreams.com is hands down my favorite website to shop for my tootsies and now my non-pant leg layers. i have a bunch of their knee socks (which are also a great alternative to leg warmers).
the yogadeal: since i've seen leg warmers on quite a few yogi friends, i thought it only fair to put them in the know about sockdreams; the company is simply great! they offer affordable, functional fashion for your feet (and legs). the wool leg warmers in this pic are only $18.