I am just about the fall into that trap now. The only (that I could find) credit card that earns Emirates miles available in my country of residence (not the UAE) is offered by Emirates National Bank of Dubai.

It requires one to maintain a fixed-deposit account at the bank first of all, with a minimum balance of AED 150,000 (about $40K) for the Platinum level and AED 250,000 for the Infinity card. The interest rate on this account is about 0.5%, maybe not horrible by U.S. standards these days, but two points less than I could otherwise get in this part of the world. These funds are locked for a year at a time -- one can withdraw the funds any time, but one forfeits the interest; no big deal I guess given the rate.

Then you have to maintain in a normal savings account at the bank with a balance equal to or greater than the card limit, to cover in case of default. That is on top of the fee for the card, which is AED 700 per year for Platinum and AED 1,500 for Infinity, and non-trivial bank charges to wire the money internationally to set up the fixed account and to transfer the funds into the savings account to pay the balance each month.

At least the earnings rate is pretty good -- 1.5 miles per $1 spent on the Platinum card or 2 miles per $1 spent for the Infinity card.

So I calculate that if I spend $7,000 per month on the Platinum card, it would cost me about 1c per mile (Infinity would cost more), given the cost of the card and the foregone interest. This does not take into account the opportunity cost, besides the foregone interest, of the illiquidity of this fixed-deposit account, nor the small risk of having money stuck in UAE for who-knows-what-reason. More importantly, it assumes no other charges, especially interest, which would quickly make this a bad deal. Obviously it would be a lot more attractive with a spend like $20,000 per month.

Let's hope I can put these Emirates miles to good use! First-class A380 or SFO-DXB here I come!