I've always liked the thick socks. If you want something for over the knee, try a pair of sleeves.
http://www.motosport.com/dirtbike/product/ASTERISK-CELL-KNEE-BRACE-SKINS-PAIR/?id=108517
http://www.motosport.com/dirtbike/product/EVS-BRACE-SLEEVES/?id=101976
http://www.motosport.com/dirtbike/product/ALPINESTARS-KNEE-SLEEVE/?id=120672
Well, I have thick socks but man after riding all day my feet are drenched, I have the booties in my boots. And for way less than $20 I can got snatch a pair of leggens off womens rack at Wal-mart and cut them, no ones gonna see anyway.