unfortunately i have a very low limit on my spg amex....so when i am travelling upto 2-3 weeks in a row (which i do very often) then i can't use the card as it gets maxed out....so i use cash....also, in some countries i get hit with a very bad exchange rate by amex, so i pay cash instead....& i have enough points on all my frequent flyer programs, so getting a few more by paying through a branded credit card is not really an exciting incentive for me, specially when i would get a bad rate or have to make a dozen payments a month to clear some limit on my card....