Calling dKos Savvy Travelers: HELP!

I need to buy a transatlantic roundtrip ticket.  I've stopped hyperventilating about the ticket prices being astronomical.  I feel reassured that I can check out the possible seating on Seatguru.com.  What freaks me out is not knowing whether or not I'm getting the best deal possible given my date restrictions and preferences.  I need Kossack input!

The route is Columbus Ohio to Madrid, Spain.  Autumn.  I don't have any frequent flyer miles.  Gotta pay for it-- all bloody thousand plus dollars of it.  I prefer to fly Delta because the planes are better transatlantic.  But if I go to Delta's website, is that the best I can do?  The possibilities at Delta.com beat Expedia's limited offerings.  Is there a better airline to fly than Delta?  I've done Continental but they're not so great.  No way will I do American as I don't want to get on an Airbus plane for such a long trip.  And what's the best bargain place to buy a ticket?  I'm not sure about Travelocity; never used it for a flight purchase like this.  Anyone have any suggestions for where they'd buy a good ticket or check things out?  Who has a favorite site to go to for travel?  Who has some good savvy traveler buying tips for flights?