I am not going to do stud walls...that would just add back the cost that's gone from not stick framing. Horizontal 2x4 girts at 2' on center will hold whatever I decide to put on the walls very securely. The final selection for wall covering will not come until later because of cost fluctuations. One thing that will not be on the walls is ordinary OSB...I hate the stuff. With a passion. I honestly do not have any aversion to sheetrock as it's not my practice to screw things to the wall wherever and I'll likely use a cleat system for hanging things with the cleats centered over the girts. Because I opted for the laminated posts, the walls should be pretty darn flat and straight, too...it really makes a difference.
To help you visualize how interiors are often done for post frame, you might enjoy watching this particular RR Buildings episode from a few years ago that deals with that subject: https://www.youtube.com/watch?v=fvzJna_SrwI
Interestingly, the material for cleats will essentially be free as I just got dibs to rip out all the #1 1x4 and 1x6 pine moldings from the "horror show" house next door that's going to be demolished in a couple of months. It's some of the little bit of salvageable material from the house...very sad that the previous owners didn't do any maintenance for...decades. A neighbor down the street who is a builder and his spouse (who is a Borough council member) bought the property to rehab and resell, but later discovered so much hidden water damage and other structural issues that it's been determined recycling, demolition and juet reselling the lot for more than they paid for the property "as is" is the best financial course. They really wanted to do something nice for the neighborhood, but "no good deed goes unpunished" was in full force. So if anyone wants a nice .375 acre lot and to be my neighbor...