My currently favorite method for tuning the room is to go the main middle mic and have the assistant raise my level up to very loud. This achieves 2 thins:
1. I can hear and reduce feedback from mains in a more than real life situation, giving me some peace of mind. It's a better approach then just ringing out speakers because I actually excite what might feed back, and I know better when to stop.
2. I can further hear artifacts and resonances around the stage and back from the hall, and all the muddy stuff. Since the mains are turned away from me it's actually listening with a LPF, which makes easier judgement.
After that I go to the sound post and listen to the system, not surprisingly I often have some high frequencies to take care of, while the low (but not lowest) end is taked care of.