In my first winter as a runner, a friend suggested I try Smartwool socks. With a drawer full of 2 for $5 socks at that time, I was admittedly a bit shocked by the $20 price tag, but quickly discovered those socks were worth their weight in gold. Five years later, I still have that pair of thick winter socks, and they are the only things that keep my toes from going numb on longer winter runs when the temperature dips below -20C.
So, I adored that one pair of Smartwool socks, but thought of them as strictly winter socks. wool = winter gear, right? Wrong, actually, as I learned this summer when I picked up the PhD Light Elite Low Cut and Micro socks. http://www.runningfree.com/products/Smartwool-658/SW-PhD-Light-Elite-Low-Cut-p47688/?pstart=1
These socks still seemed pretty thick to me, so I was a bit skeptical of how they would fare in the hot and humid weather we got through September, and whether they would fit into my snugger fit racing shoes. I first tried a pair for a tempo run, then for a 36k long run, and ended up wearing them for my fall marathon. The socks do feel thick to the touch, but they fit like a glove, and I found my feet were less sweaty in them than in other socks. If you are prone to blisters, this would probably be a great thing.
Overall, a very good sock, and the only cons might be that there are not a lot of colour options, and the price tag might be a bit shocking at first if you are a newer runner used to buying cheaper socks. But I suspect they will last much longer than a cheaper sock, making them well worth the price in both quality and longevity.
At the very least, do yourself a favour and pick up a pair for colder weather running. Winter is coming.