Originally Posted by
Genius1
You need to purchase World Traveller Plus (premium economy) to upgrade to Club World (business class). This will cost 25,000 miles return between North America and the UK.
And you will earn WTP airmiles from ATL to LHR, so you shell out 25k miles, and get back 10k or 20k miles, depending on your status. The 150 tier points obviously help with status, and there are some clever ways of getting tier points "cheaply" using AA.