Credit card © Corbis

Do you spend a lot on your credit card? If you do but don't use a credit card that earns you the best rewards, you're not getting the most out of your money.

Rewards cards vary significantly in terms of the areas where you can rack up big points -- some cards offer better rewards for hotels and flights, while others yield higher returns for gas and groceries. But the best cards require excellent credit to qualify, generally scores of 750 and above.

"They're great cards, which means you have to have great credit to get them," says Beverly Harzog, an independent credit card expert and consumer advocate. (Know your credit score? Take this MSN Money quiz to get a free estimate.)

A great rewards card will enable you to bank significant discounts on hotels and flights, while others will earn you large amounts of money in cash back on everyday expenses like groceries and gas. However, a rewards credit card isn't a good option if you can't pay off your balance in full each month.

"If you carry a balance, the (annual percentage rate) is going to eat away all the rewards you earn," says Bill Hardekopf, a credit expert with LowCards.com.

"That's always the trap for the cardholder: They'll get so excited about earning rewards that they charge more than they can afford to pay off in full, in which case rewards can become very costly, very quickly," says Gerri Detweiler, the director of consumer education at Credit.com.

Many rewards cards carry higher interest rates than standard credit cards do. As of mid-August, the average consumer rewards card's interest rate was 17.64%, versus 15.15% for a non-rewards card. Annual fees are also common for many rewards credit cards, with most starting around $59.

However, a $7 billion settlement with Visa, MasterCard and several major banks in July over interchange fees could adversely affect what consumers have to pay for using a rewards credit card. The settlement would reduce the interchange fee that banks can charge for the next eight months and would enable retailers to charge fees on each swipe directly to consumers who use credit or debit cards, so the banks can make up the costs.

"If the credit card interchange fee gets sliced dramatically, that can affect the rewards that credit card issuers can offer," Hardekopf says, since banks make a large chunk of their money off the interchange fees. If the banks and credit card companies scale back the interchange fees, they'll make less money on each transaction, which could mean they'll no longer be able to offer such attractive rewards on their credit cards. Some critics have gone so far as to say this could mean the end for rewards credit cards.

Yet a number of major retailers, including Wal-Mart and Target, are opposed to the settlement. With such significant opposition, Harzog believes it will take a while for consumers to feel the effects of the settlement. Harzog and Hardekopf say they don't think the settlement means the end for rewards credit cards.

For now, rewards credit cards offer lucrative perks for card users, and the potential rewards are greatest for big spenders. U.S. News asked credit card experts for their top picks.

PenFed Premium Travel Rewards American Express Card

Harzog says this is a great card for frequent travelers. Cardholders get five points per dollar on airfare and one point per dollar on all other purchases. They can also earn 20,000 bonus points if they spend $650 in the first three months. The interest rate is also attractive, at a variable 9.99% until June 30, 2014 -- meaning the rate can only decrease during that time.

There's no annual fee and no cap on the amount of rewards you can earn. "Big spenders want to know they can earn unlimited rewards: otherwise they have to start shuffling cards," Detweiler says.

Capital One Venture Rewards Card

This card is also a winner in the travel category. It offers two miles per dollar on every purchase, with unlimited miles, and you can buy any airline ticket or hotel room you want, with no blackout dates. "I've had this card for about a year and really like the flexibility of being able to get airline seats and hotel rooms without hassle," says Liz Weston, an MSN Money columnist and author of "Your Credit Score." "Also, it has no foreign transaction fees, which made it a great choice for a recent trip to Europe."

Users can earn 10,000 miles if they spend $1,000 in the first three months. The card's $59 annual fee is waived the first year.

Blue Cash Preferred American Express Card

Weston and Detweiler recommend this card for its high cash-back rewards. Users get $150 cash back if they spend $1,000 in the first three months. The cash back varies by category: 6% at supermarkets, 3% at gas stations and department stores and 1% on all other purchases. There's no cap on the rewards you can earn, and the rewards categories don't rotate, which means you don't have to enroll each time if the rewards were to change in each category every few months, as they do with some cards. The card has a $75 annual fee.

Chase Sapphire Preferred Card

Detweiler likes this card's sign-up bonus: Users can earn 40,000 bonus points if they spend $3,000 in the first three months. The card also offers two points per dollar spent on travel and dining, and one point per dollar on all other purchases, with no cap on the rewards that can be accrued. Users get 20% off travel redeemed through Chase's Ultimate Rewards website. They also automatically get a 7% annual points dividend on all the points earned throughout the year. There are no foreign transaction fees, and the $95 annual fee is waived the first year.

Starwood Preferred Guest Credit Card

Users automatically earn 10,000 Starpoints after their first purchase, and earn an additional 20,000 points when they spend $5,000 in the first six months. There are no blackout dates for redeeming points, and you can choose from more than 1,000 hotels and more than 350 airlines. The card's $65 annual fee is waived the first year.

Chase Freedom Credit Card

Hardekopf and Harzog say Chase Freedom is one of the best cash-back cards. Cardholders earn 5% back on up to $1,500 spent in specific categories like gas stations, restaurants, grocery stores and movie theaters. However, the cash back for these categories changes every three months, and users have to sign up each time, which takes a lot of effort. Users receive $100 cash back when they spend $500 within the first three months. The rewards are unlimited, and there's no annual fee.

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