[Sunnybride]

Originally Posted by Arubalisa

Delta's cheapest tickets are fare classes are --L, U, and T.

When you search at delta.com by price these are the fares which will be shown first, with the exception that these fare classes or "seats" are already sold out. Obviously there are sold out because they are the lowest priced.
Delta does not sell upgrades to people who have booked L, U or T tickets.
When you see upgrades at the gate for $150 to business class on a flight to Aruba, if you have these fare class tickets above, no amount of pleading will even allow you to PAY for the upgrade.

If you do not book one of the discounted fares above, keep an eye on the difference between business class fares and your coach class fare.

One trip we booked extremely expensive refundable coach class tickets. As we got closer to our departure and were checking fare prices, discounted business class was cheaper than our original fare in coach. One phone call to Delta and they changed our tickets from coach to business and refunded the difference.

Even if your ticket is non-refundable, sometimes even with the cost of ticket change fee you could be paying a similar fare in business class for what you paid for your full fare non-discounted coach fare. If you were paying the same price would you rather fly coach or business class.

To upgrade with miles see Delta Upgrade AwardsAgain, only certain fare class tickets are upgradeable to business class with miles. If there is an upgrade available at least you are able to calculate in advance whether or not you want to spend the extra money for a coach class ticket in order to upgrade for the miles.

We're flying with american airlines, does the same thing apply?