I plan to wear the same shoe/sock combination on the AT that I wore on the Camino de Santiago. On the Camino I was one of the very few people who did not get a blister on the 500 mile walk. The only thing I can attribute it to is that I am an experienced hiker and that my shoe/sock combination worked out perfectly. For me, I need shoes that are not too tight around the forefoot and that have a large toe box so that I can wiggle my toes from time to time.
A little warning here…everyone has different feet (you knew that already didn’t you) and what works for me may not work for others. The important point is to log a lot of training miles in the same shoes and socks that you will wear on your hike and make sure that the combination is right for you. You’ll know it’s right if after long hikes (8-10 miles) you have no friction points that become hot spots and eventually blisters.
On the Camino I wore a pair of Keen Voyageur hiking shoes that I had been hiking in for about a year. A couple of weeks prior to starting the Camino I purchased a pair of green Superfeet which initially felt stiff but after two or three ten-mile hikes they felt great. Finally, socks are just as important as shoes so I spare no expense and use Smartwool running socks that come to just above my ankle. The socks are real thick but are not super thin either.
I used two pairs of the Smartwool socks and alternated the from day to day. At the end of each day I washed the socks. The only time I switched out the socks during the day was when I walked through drenching rain from Santiago to Finisterre. I was concerned that my wet feet would be more prone to blisters but that did not turn out to be the case.
Here’s a photo of my Keen Voyageurs after five days on the Camino. You can see that they’re already pretty rough looking. They lasted the entire trip but the heels were significantly worn down on the outsides so I retired them once I got back to the States and purchased a new pair at REI in Richmond, Virginia.