Okay, you’re probably going to laugh at how over-the-top I am. 
For the cards I carry, I have a label-maker sticker on the top to remind me (picture below). They are in my wallet in order of preferred use, so I use first one that applies. I don’t carry the Amazon Visa since it’s mostly used on the Amazon website (stored there) and I just remember to use it via my Apple Watch when I’m at Whole Foods. I only use the Costco card for gas since the Fidelity card is just as good for everything else. I do have to periodically check if I’m close to the $1500 limit on the Chase Freedom, which I have a calendar reminder for. When I get there, I take the card out of my wallet.
She doesn’t mind. I do the vast majority of the shopping. She occasionally uses the wrong card, and I just ignore it.
I don’t do Walmart, so that’s not an issue for me.
Yes, TJ counts as groceries for both Amex and Chase Freedom.