I find most Citi cards can buy GCs at stores and the transaction will be a purchase not a CA.
To ensure this actually does happen, it would be great to not even have a CA limit on your CC.
However, Citi is the only CC company that lets you set your CA limit to $0. Do this first and get it in writing.
However, reports are that Citi AMEX CCs do not allow this feature and that using one of those will treat a GC purchase as a CA.
That said, many other CCs will do the transactions as purchases too, even if those CC companies will not allow you to set your CA limit.
I hear US bank may be a CA so be careful with them as well, but most others should code as a purchase.
I can say I have used many cards for many things and changed cards over the years/months, and that all my Chase, all my Amex and all my Citi among others, have never had a problem. All things have been purchases, no CAs.
I do not own a US Bank or Citi Amex card.
Btw, buying AAA products can also be leery. These may go thru as CAs if they even let you buy with a CC anymore, which I hear is only very rarely and sparingly allowed. I no longer have a membership to AAA and don't plan on rejoining right now.
Cashing out GCs is a different story. People have many methods. Don't bother asking in this thread. I can say that many here, self included, have simply bought them to make a spend or two or three, and then spent them as normal, knowing I have more time on my clock to do so, but the spend requirement and its time frame have been fulfilled and the bonus miles posted in the meantime so it's ok.

MM