What can I do to avoid tripping over HVAC drain line?
I'm imagining it's only a 1/2" pipe, in which case maybe an on-floor cord protector might work: http://www.homedepot.com/p/Legrand-Wiremold-5-ft-Over-Floor-Cord-Protector-CDBK-5/100669770

Or you could re-route the pipe around the perimeter of the room to avoid the heaviest traffic.