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I don't know anything about the Amex and Citi travel portals, but if your long-haul flights are in premium cabins, Amex offers its Platinum card holders access to its International Airline Program, which can offer significant savings on intercontinental airfares. The personal Platinum card has a hefty annual fee, but there are generous sign-up bonuses currently being offered for the card, so getting it for at least the first year could be worthwhile. After one year, you could then decide whether it makes sense for you to renew.