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Originally Posted by
clacko
the choice is really dl or *A which will be ua/co & us.....wn is also a choice...
Translation:
"The choice is really Delta or a member of Star Alliance (United/Continental which are merging or US Airways) ... Southwest might also be a choice."
Since its DFW American really is the best choice for frequency/destinations. Any other airline will almost certainly require multiple segments to many destinations that didn't require transfers before. For the destinations you've listed I think United is the second best choice (could be wrong on this).
Since you mention wanting to vacation in Europe using miles that rules out Southwest (since they don't fly internationally).
As for award redemptions Delta is probably your worst choice. They are nearly universally disliked for their miles program here on Flyertalk, which many people call Skypesos because of how little purchasing power they often have. They can be good to travel to Europe if you are leaving from a major East Coast city so you can redeem on partner airlines directly. But redeeming Delta miles for Europe trips departing from DFW I would expect to be very difficult, as Air France (a Delta partner) doesn't fly to DFW.
What this means is a Europe trip would most likely involve going to Atlanta first, and then flying across the pond from there. The DFW-Atlanta leg might be hard to find availability on, so it limits your possibility of getting to Europe. You will likely end up paying more miles than you would like or have very limited schedule options.
Delta's frequent flyer program has it's strengths, but if you're one of the many that falls into the category of a businessperson who travels a lot domestically in the US and earns miles that he/she wants to use by vacationing during school holidays with his/her family in Europe.... then Delta is about the worst there is.
For redemptions US Airways or United will almost certainly be better. I'm not a resident of DFW though so maybe someone here can speak to that locale better.
So I guess I would recommend United although I'm no expert by the standards of this site and have never lived in the DFW metro area.
Since he has lifetime Platinum it would be natural to try out another airline for a year (to get status) and then switch back if he has issues.