Thanks for the nice comments!
Adult socks are usually 7-8" in circumference so I just need one needle and can knit in the round regularly on it. Since you can stretch your work a bit an 8" needle is fine for socks a little less than 8" too. I have small hands so the needle isn't crampy for me but I have heard others complain that these needles are too small. I love making socks on 2 circulars though too!