As a Platinum, I am over 80% on upgrades on the lowest advance purchase price possible IAH to PHL and return. My wife is about 50%. My wife usually takes the first flight Monday morning at 7:30, upgrades on this flight are nearly nonexistent - partially the time and partially there are only 12 seats in first. Yesterday, Friday, on the 7:30, I was a standby and upgraded as a result of 18 first class seats and the day of week. The IAH - PHL route varies the number of FC seats. Friday afternoon PHL to IAH is not a good time. The 6:15 am PHL to IAH has the 18 FC seats and is a good bet for upgrade.