I really like the individual tack areas. We are all in a room about 8x12. We have individual space but things get moved around. Another thing is that we have two tie poles. First come, first serve. After taken you tie in front of stalls. The walk way gets crowded sometimes. Lot's of lights too.
I think there would be cross ties at each stall, or tie rings to the rail of the arena, but yeah, it can get crowded and any width I can spare for aisleway would not be wasted!
And light is important. There would be lots of lights, but I also would have not only the windows above the stalls for daylighting, but skylights in the roof. I hate dark barns.
I've done the common tack room thing too, and hated it. stuff gets moved or borrowed, saddles get scratched, and I really like individual storage with a key.