If most of your travels are in a part of the world where Amex isn't taken, then you're probably going to want a general spend Visa/MC with no FX fees that awards something other than hotel points.

Get the Marriott and Hilton Visas that more than pay for themselves. Use them at hotels and (perhaps) in any "bonus" spend categories if you like. After that, maybe get your airline's card if its signup bonus is worthwhile and it provides some perks to offset its fees. Or get a cashback card.

Your interest in these cards to begin with - plus a mention that your travels take you to places that don't take Amex - leads me to believe you're U.S.-based with a lot of international travel. Don't overlook the FX fees on any card you consider.

The Marriott Visa, for what it's worth, has low FX fees - around 1% Amex is usually around 3% No idea on the Citi Hilton card.