dansil: one exception would be CO. If you are Gold Elite and show up at the airport 2 hours from flight departure and there is a seat in F, you get it. No upgrade certificates needed at all! It doesn't matter what fare inventory you're booked on either. If you are traveling with another passenger and there is a second seat available in F, your companion gets upgraded too. Regarding DL: well, we all know about those L fares.