Originally Posted by
84fiero
Plus you have a number of cards earning Amex Membership Rewards and Chase Ultimate Rewards, that transfer to DL and UA, respectively (a little more planning with Chase as you need to have certain cards open to do transfers to partners, but not hard to do). So plenty of earning opportunities for those two FFPs without even repeating any one card. Though there are other transfer partners for both MR and UR that may be more worthwhile than DL/UA to consider, depending on your situation and goals.
Yes, totally forgot about MR. Although personally I'd rather use MR on other programs. Skypesos aren't a "good" return, IMO unless you want to fly domestic economy (I live at an airport where there's never any cheap Skymiles flights and their Flash deals are never out of my home aiport either.)
UR on the other hand, is easily churnable (I wouldn't chance any self-referral CIP at this point either), although with UA dynamic pricing, probably better off with other programs, BUT you get more UR on a SUB than UA MP for the same spend, IMO.
Good points about the MR/UR options. Always good to have flexibility, IMO.