Proxy Auto-config

I'm installing Squid in our environment and want to use it in non-transparent mode. I made a wpad.dat file and set my hosts file to direct to the server where I hosted it (for testing). Now the question is how do I roll it out in full? I know some of my options (DHCP, DNS, GPO), but is there a preferred method of those 3 (or something else I haven't seen)?