We basically agree. So I'll post only one more clarification (for now...). What we disagree about is not 'should I maximize the number of miles and points I earn from what I do anyway, like flying and staying in hotels?'. The answer to that is (almost) always yes. The question is 'should I use a credit card to get more miles?' You opened this thread by saying 'yes, of course'. I disagreed by saying 'yes, you should choose to get some kind of reward, but for many people cash is better.'

Credit card spending is the rare case where you can choose between getting extra money (rewards) and extra miles (rewards) - so, if you like, the miles are fungible at the time you choose what credit card to use and so whether to earn them. So you should use your valuation of a mile to decide. If you're getting 2c - 5c on the dollar with cash reward cards, then your value of a mile must be more than that, or else you're making a mistake. For people flying in F or staying at the Cavalieri, the correct valuation may be more than 5c per mile. I understand that. But if you check out the MR forum, where there are many threads on this, most people use a valuation of between 1 and 2c. In the case of credit card reward choice, since you are making a direct choice between the cash and the reward, the 2c-5c per dollar cash reward is your real opportunity cost. So for most people, including most people on FT, the cash rewards are a better choice. Particularly if, like many people on FT, you are already earning more miles than you can use anyway.

chauming: Sorry if I sounded rude; it wasn't intended.