We do the same thing with our amex account. I’m sure amex doesn’t like giving bonuses to folks that never carry a balance, but I’m OK with it.
Our local Walmart, to my knowledge, has never accepted amex. Menards doesn’t either. I asked why not and they said amex charges them more per transaction than other companies.
I carry both a discover and a visa, set up for cash back rewards....each has an advantage for certain types of purchases.....gotta check out each card and read the fine print..we also will take advantage of those 6 months same as cash type deals, if it is something we really need....nothing feels quite as good as using someone elses money for free ( but if you are 1 day late paying off the balance at the end of 6 months, you will get hit with tons of fees, so send in your last payment real early )...