I finally got a Diners Club credit card, and it turns out to be indispensable for the frequent flyer.

It’s my new favorite credit card, more so even than my Starwood American Express which I still carry and love.

The Diners Club card —

• Has the most extensive rewards program out there. I still like Starwood’s mileage earning, especially for its bonus of 5000 miles when converting 20,000 points. But Diners Club offers at least one mile per dollar on the airline or hotel of your choice, you get to pick later, and it has a more extensive list of transfer partners than anyone else.

  And there are always bonus offers running, whether it’s 30% bonus for converting points to United or (it seems like each summer) double miles for transfers to British Airways.

  The program is a bit confusing — you earn 2 points per dollar spent, and those two points convert to one frequent flyer mile at least. Joe Brancatelli did the math and non-mileage rewards tip in favor of Diners Club, too.
  
• The single greatest benefit, to me, is the rental car insurance. Many credit cards offer some coverage that only kicks in after your regular insurance which makes it almost worthless. If you rent a car using your Diners Club card, Diners provides primary coverage. Anyone who rents cars frequently should get a Diners Club card strictly for this benefit.
  

• The card allows you to transfer United and American miles into Diners Club points. You’ll see a 50% devaluation (or less if you transfer during a bonus promotion), but it allows you to move miles around your different accounts.
  

• The best customer service going, with no voice tree hell, and even a network of airline lounges that card membership provides access to.
  

• Gives up to two billing cycles to pay, roughly 60 days, meaning that late fees are almost never an issue and you can even carry large balances and pick up the “float” (interest, or in my case both interest and miles on my checking account balance)

The fee is ‘steep’ at $95 per year, but I understand that you can use points that you earn to pay the fees after the first year. And it’s only $10 more per year than the United Gold Class Visa or the American Airlines Platinum Mastercard. Besides, the signup bonus (see below) is worth fare more than the annual fee.

The other drawback is acceptance. It just isn’t as widely accepted in the U.S. as in many places around the world. Airlines take it and so do most hotels and Best Buy and gas stations and I’m finding plenty of uses for it. But it just isn’t the “one card solution” to all of your charging needs. My local drycleaner doesn’t take it, and neither does my supermarket (but they don’t take Amex either).

I think I’ve settled on a personal solution of Diners Club, Starwood American Express, and Amtrak Mastercard. The Amtrak Mastercard is free and points transfer to United, Continental, Midwest Airlines, and Continental.

If you’re interested in getting the card, the signup bonus is generous. Several airlines offer links to the card, but those often limit your bonus options. The best bonus — or at least there are none better that I’m aware of — gives you 24,000 Diners Club points during your first year of membership which convert to 12,000 frequent flyer miles in the airline of your choice (or 24,000 miles with British Airways if converted during a double miles promo).