I agree with
@Jen and Ashwin, your Amex SPG would fall off your credit report 7-8 years after you close it so it wouldn't be helpful for you to close that card in the short term. 17 years is a long time. If it's your oldest card, or close to it, you'll probably take a big hit on your average age of accounts metric for your credit reports, especially if you're considering opening up a bunch of new cards.
I'd suggest the next time the Amex SPG's annual fee posts, call Amex's retention line and tell them, after 17 years, you're considering canceling the card because you can't justify the annual fee; ask them if they can offer you anything that might help you make the decision to keep the card. You might be offered a statement credit or points after spend that could offset the fee. It helps if you've put a good amount of spending on the card in the year leading up to the annual fee so they see you as a customer they want to keep. Since SPG points have such great redemption value, I wouldn't mind charging non-bonus category spending to it. I know several posters in this thread use their Amex SPG as their daily driver.