Well, it's been a quiet weekend and I've had plenty of time to research this hiking sock thing. Using all of your suggestions about fibers and plenty of google searches, I think I'm going to go with a fingering weight, wool blend, machine-wash yarn that has some stretch to it.
Here are some yarns that seem suitable for hiking socks like SmartWool retail brand socks:
--Soxx Appeal from Knit One Crochet Too [96% superwash merino/3% nylon/1% elastic]
--Regia Stretch [70% new wool/23% polyamide(nylon?)/7% Elite(stretch polyester)]
--Lana Grossa Meilenweit Mega Boots [70% virgin wool/23% polyamide(nylon)/7% Elite]
The cost is similar for all three yarns because the ones that seem less expensive will require 2 balls for a pair of socks, instead of 1 ball per pair for the more expensive yarn.
One person on the web who knits hiking socks for her husband says that she uses 2 strands of yarn for the areas that need extra cushioning.
Any thoughts on these yarns or the direction I'm going?