American Airlines' Solid No Annual Fee Credit Card

Will the MileUp CC prevent AA miles from expiring?

Yes. I downgraded my fee card and kept it as a no fee card for that purpose.

Sure will. I have the card; easy to earn miles and loyalty points. Also, you can earn miles by registering it with Simply Miles, as an example. Not my main credit card, but it has its plus points.

To renew my AA miles the coffee shop one block over from me is part of AA dining. So just a cup of coffee there now and then with the CC I have on file with AA will do the trick.

Should I get the no fee card with the signing bonus now and then cancel the fee card? Are there any benefits for getting no fee card at the moment of cancelation?

Can you hold multiple citi AA cards of the same type? For example, can you get this card (Mile Up) and later downgrade the Platinum aadvantage Card to a Mile Up one, resulting in two exact same cards?

Sorry, I probably should have been a little more clearer. I was actually referring to just keeping the $0AF MileUp CC open as a method to prevent AA miles from expiring without having to do any transactions whatsoever to reset the 2yr expiration clock. Do you know if that works? Asking for other household members with AA miles that aren't active travelers. Thanks.

I'm pretty sure holding this card as the primary cardholder automatically keeps your miles from not expiring. The AA AAdvantage MileUp is the only AA credit card I possess and I have this blurb on my AA account page...

"Primary AAdvantage® credit cardholder - no miles expiration with open card account"

So you should be good. as a primary cardholder.