Well, I have nose bleed seats and I love 'em There are very few 'bad' seats at Heinz.
I"m not sure about the site you're buying your tickets from. I always tell people to go with the ticket exchange service that on the steelers site. It's safe and all the tickets are coming from season ticket holders.
Since the season ticket holder don't get their tickets delivered until July, I'd be wary about buying them from another site so early.
I would sit anywhere between Sect 536-528 or 509-517. You'll get nice view of the field as well as the jumbotron. If you're on the even numbered side you'll also see the skyline. Since the rows start with A,you can be the judge of how far up you want to go. I believe the last row is LL or MM.