Here is a thought. I signed up our personal Visa, work Visa, and debit card to receive UA miles for dining.

We never even bother to look up which restaurants take the card or not. I.e., we focus on food quality, price, etc. Still, considering that we (spousal unit and myself) charge about ten meals per month; we are not looking too bad to have one in ten show up on our statement as having earned miles. I.e., blind chance results in miles here and there at random.

No, this is not as effective as looking the restaurants up, going to the specific establishments, etc. But, sure as heck works and there is no time/money/paperwork involved other than the initial sign-up.