rfuerst911sc,
I got my idea from the garagejournal also but it was your original tongue and groove with urethane varnish proposal. Luckily, there was a store not-to-far away that had some 3/4 " thick, 8" wide 16' long available for $0.59/ft. I did my entire bonus room/man cave for about $500. My space is 40' long by 10' wide. Just the final, final trim work remains on the gable ends. We still need to install proper light and ceiling fans (mini-split already fully operational) yet my wife and I already spread a considerable amount of time in that space. We used my Harbor Freight 18 gauge nailer with, I think, 1-1/2" brads. That nailer was probably one of the best 'less than $20 purchases' I have ever made. I have shot thousands of brads with a total of two jams. Our attic trusses are like yours with 24" spacing.
We cut 45 angles on the ends of the joints. My neighbor did a strict butt joint and I think that the joint we used looks much cleaner and better.
