I had a good supply of 1-1/4" galvanized pipe in 4' sections so ran those up the wall then down the center of the shop with tee branching off the top then 1/2" line to wherever I wanted a drop and ran the 1/2" down to those points.
I did incorporate a "drip leg" in the vertical line going up the wall with a manual drain in the bottom.
So far I have had zero issues with air in the lines regardless of what the weather conditions have been.