Personally, I have a Schwab AmEx that gives me cash back immediately to my personal brokerage account.

As far as travel cards, I have the United Club Card Visa from Chase. Basically comes out to $440 a year with the annual United employee credit posted every March. If I visit a club alone 7-9 times a year it pays for itself, fewer visits if I bring in my first officers or partner. I do use it for long sits between flights as well when able and bring my FOs if they don't have club access themselves.

The other is a Marriott Boundless Visa from Chase. Start out the year with 15 nights credit and only need 35 stay credits to get platinum status. The $95 annual fee is easily paid for with the free night every year. Depending on the sign up bonus being offered at the time you apply you can definitely get a generous point credit to your account.

I agree with others about credit card interest. Since my second year at the old Continental Express when I was really making paultry money and had to use my CC, I have never paid one cent of interest in 25+ years. Use it like cash and make purchases only when you know you have the cash in your account to make that purchase. From there you can get a lot of perks and freebies. I have three other credit cards I never use after opening them for generous cash back statement credit when I was going to make big purchases around the time.