Having enough outlets is always nice!
I piped air from my big shop, through the workshop, basement in the house, and attached garage to the house. I ended up going with Pex-Al-Pex heating pipe. It's really cheap, connectors are cheap, it pulls like romex wire, and it's fast to hook up. I did use the copper crush ring style crimps, and did double ring just to be sure.
Might be something to consider if you want to run air pipe. Be sure to get oxygen barrier pex. Regular pex will seal the air, but without the metal in between pex layers it can balloon out an pop (or so I've heard). 300 foot roll of 1/2" Pex-Al-Pex was around $70 when I piped everything up. Local heating and plumbing supplier sold me the connectors I needed, and even let me borrow a crimper for the weekend.
Dan