I don't know what you're looking for cerebrex...something that is not there?
It is time to be cerebral about this. I think the suggestions you've received are the best ones available...short of mounting it flat on the ceiling and laying in a prone position whenever you desire to watch.
I mean, you've got the 6' glass door smack in the middle of one wall, the back wall is nonexistent as it is open to the kitchen, with lots more glass and formica...hmmm...love those reflections. Your next wall has an opening to the foyer, and your front wall has yet another door opening and a large brick fireplace. All in a fairly modest sized room. The only other options I see are the front corner, or the back opening (to the kitchen). This is one of those less than ideal situations where you're 58" Panny is going to have to be squeezed in with a shoehorn, I'm afraid. I do wish you the best in optimizing your screen location, but the room that you've selected is a tough one for such a big screen. I think you'll have to settle for less than ideal in this situation. Cheers.