have a citi AAdvantage--->

Miles earned on the card do not expire as long as you have qualifying activity on your AA frequent flier account at least once every three years. Charging on the citi card just once every three years qualifies so expiration is not a problem.

You should get bonus miles for applying. These range from 5000-10000 for the gold card and possibly higher for the platinum.

The gold and platinum cardholders get reduced mileage awards to a list of destinations which change every quarter. There are good places on the list--both domestic and international. Gold cardholders can travel for 5000 fewer miles and platinum for 7500 fewer miles to any of the designated places.

These are the differences between gold and plat: gold annual fee is $50 and plat is $85. The maximum number of miles you can earn on gold in a calendar year is 60,000. On plat. it's 100,000. All other benefits are exactly the same. Unless you intend to spend alot of money, the extra $35 for the plat. is probably not justified even with the modestly better reduced mileage awards that come with the plat. But you'll have to do your own math on that based on your own personal spending habits.

Customer service is excellent by the way. I've had the world gold version for three years and accumulated alot of miles with it.

 

Oops. Forgot the second part of your question. I prefer earning miles through the AA card because they are combined into one account with miles earned from other sources such as travel on AA, long distance carriers, rental cars, hotels and restaurants. There are so many ways to earn miles, that you can easily get a free trip without having to spend $25,000 on the credit card. With world points, you only earn miles from using the card.