If you already have credit cards it may still be well worth changing to another card with a lower APR or charges. Even with your low interest amercian express credit cards, the more you pay off each month the more you will save in interest or charges.
Did you know some credit cards offer bonuses such as money back schemes, or money off selected retailer's items? You need though, to compare these benefits with the APR, to ensure you do not lose out in this corner.
Before transferring a balance from one lender to another, check to see if you will incur any fees for doing so. It may be interest free but some credit cards apply a one off charge for doing so.
Credit cards are an easy way to obtain credit and can offer great flexibility and benefits to the cardholder. By switching your balance between cards at the right time, you could save interest.