Originally Posted by
scubaskyscott
My Work is taking me to London and Spain more often and I'm thinking of switching to BA any advice is wonderful! Thanks

Questions
For members asking for information, to help people to assist you, can you please provide:
(1) What is most important to you in a FFP?
(upgrades on travel, priority services when flying the airline, extra baggage allowance, good award redemption rates, better award access, free - discounted lounge access, etc.)
Reply: Upgrades
(2) How many miles do you usually fly each year & in what class? How many flights/sectors?
(<25000, 25000-50000, >50000 miles - <25, 25-50, >50 flights?)
Reply: 100,000 Miles Currently Plat Med Delta
(3) What types of fares do you usually buy?
(First, Business, Premium economy, Economy, cheapest)
Reply: Premium Economy
(4) Can you choose your airlines and/or class of service? Do you travel for work and/or pleasure? Choose
Reply:
(5) Which routes and airlines do you fly most often?
(US Domestic, Transpacific, Kangaroo, in Asia etc)
Reply: Domestic though as of recently to London alot
(6) What is your home airport?
(SFO, SCL, London LHR, HKG, Singapore SIN etc.)
Reply: LAX NYC LHR soon
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7) Do you have FFP status of any kind in OW or other airline? What is it? Do you have any miles banked in a FFP?
(AA Executive Platinum, QF Gold, UA 1K, LAN Comodoro, etc)
Reply: Platinum Medallion Delta through 2016
(8) Preferred Airlines? Most common Airlines flown on?
Reply: Delta KLM
__________________________
US based, with LHR as frequently-visited destination?
I would rather go with AA than BA. As a 100k flyer, you'll earn eight systemwide upgrades (which, in my experience, are actually usable and good on any fare and always cleared going to LHR as there's a ton of capacity on that route). Also, AAdvantage has no unlimited domestic upgrades for its lower tiers (this is a benefit reserved for its 100k top tier), so likely your domestic upgrade rate will be higher than you are probably experiencing on DL. Mine is something like 85%, and I usually only sit in coach during IRROPS or after last-minute changes.
While you can upgrade AA domestic flights with BA points, this is highly restrictive (only Y and B fares). Same the other way around: One can only upgrade Y and B fares on BA metal with AA miles.
Caveat: When you book travel on BA in premium economy on those London flights and want to upgrade, it's better to go with the BA program as you can use BA points for this but not AA miles to upgrade from PE to business or F. If that kind of upgrade is your primary goal, you will indeed need to go with BAEC.