Originally Posted by
raftermanfl
Also, are you recommending AA? They don't seem as strong for the NYC market so not really given much consideration, should I?
It's complicated.
DL does have a stronger presence in the NYC area, and is considered by many (most?) travelers to be better run than AA. But I suggest that you have a look at the LGA Airport Wiki, the JFK Airport Wiki, and the HPN Airport Wiki (Google each) to see which destinations each airline serves from each airport.
I'd also suggest doing some dummy award searches on each carrier's website to compare and contrast how many miles each carrier wants for your award destinations on the dates when you are likely to travel.
The decision about where to credit miles is different than the decision about which carrier you will fly the most. It's true that if you want to try for complimentary upgrades to Business Class, you would need to accumulate miles in that particular airline's FFP. But if you're not likely to get upgraded on the routes you plan to fly, you might just be interested in things like priority check-in, free checked baggage, free extra-leg-room Coach seats, and lounge access. If you were to fly AA primarily (and oneworld partners AY, BA, CX, IB, and JL for your Europe and Asia travels), you could probably get oneworld status pretty quickly by crediting to Iberia. But if you credit your flights to Iberia, you could only redeem for AA's "MileSAAver" award seats; AA's "AAnytime" award seats are only available with AAdvantage miles. However, status in the AAdvantage program won't get you lounge access on wholly domestic itineraries; mid-tier or higher status in Iberia Plus will.
Lots to consider.