I don't feel guilty -- I assume they've decided that it's better to take Amex than not. If they've decided to accept it, I'm fine with using it with them.

If it's overall a negative, they shouldn't take the cards. ARCO doesn't take credit cards at all and charges a fee for debit cards.

For the Schwab 2% card, don't you have to have a brokerage account, and what are the conditions? (Minimum balance, fees, etc.?)