We were at Aulani for ten days in January. My daughter is a big pin trader so we hit all the spots daily.
The gift shop has two books - one on each side. This is the spot that gets the most traffic.
The lava shack has a book.
Painted Sky, the teen spa, has a book but it doesn't have much turnover from trading and the staff didn't seem to ever replenish it.
The
DVC preview center was the only place where cast members wore lanyards. They don't have a book, but there are usually quite a few cast members there wearing the lanyards or the little cross body pin holders. Their stock seemed to change quite frequently.
Auntie's Beach House no longer has a pin book.
People were very friendly every where we went to trade pins. They kept listing off all the other places at the resort where we could trade, but no one ever mentioned the concierge desk so I suspect they may no longer do it.