Kerri Westenberg
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With the first installment in our "How we travel now" series, on flying, we included tips on making Delta's dominance at MSP work for you. Among the pointers: Book the cheapest flight no matter the airline — but get a Delta-branded American Express card for the perk of checking free bags and the free flight that miles could eventually earn.

A reader wrote hoping I could help him and his wife settle a disagreement. She is convinced getting cash back from their Visa card is better than using their Delta-branded American Express. He prefers the Amex. He also wondered if they should upgrade from the Gold card to the Platinum card.

I'll attack the easiest question first. The Gold card, at $95 annually (after the first year, which is free), should do the trick and will pay for itself if you travel frequently enough and check bags. Delta charges $30 one-way for a checked bag on flights within the U.S. That's pretty simple math. The Platinum card ($195 annually) also gets you a free companion seat. That boost up the card ladder would easily pay for itself if you use that free seat. But the truth is, such seats are difficult to snare, often requiring weird layovers and off hours. Most years, I forget the perk even exists. Once I tried to book the free seat and decided to skip it because I value my sleep (I was offered a 5 a.m. flight). Readers have written to complain of how difficult it is to find a companion seat. Still, for those with flexibility and tenacity, the extra $100 is worthwhile.

As to the more difficult question — using a cash-back or Delta card — it comes to personal choice. People who fly more often will benefit the most from a Delta card. Delta purchases made with the card earn double the miles. Earn enough through all sorts of spending, and you can raise your Medallion status, leading to benefits like early boarding and free upgrades. But many experts agree with the wife. Cash back can be used to upgrade or pay for checked bags, too.

Send your questions or tips to Travel Editor Kerri Westenberg at travel@startribune.com, and follow her on Twitter: @kerriwestenberg.