I have had the Delta Gold card for 5 months. I signed up for it when I was targeted with 50k signup. It was perfect because I was flying Delta in January and could use the miles. I also used it to get discount entry into SkyClubs so I thought it had decent value to me at the time. I only used it 3 times total and didn't plan on using it much since I have a PRG, Hilton, and new Platinum card. Yesterday I got an email offer for 0% APR for the next 6 months. So now the card has a little more value to me in case I need to make a big purchase. I'll probably cancel the card before the AF is due at the end of the year anyways.
One question I do have though...I have a few flights planned on AA,UA & WN. Might be able to make one of those flights a DL flight. Would I still get a free checked bag if I pay with my Platinum, but present the DL Gold card at check in?