...cards? All I know of are earning mileage through hotel stays and from grocery shopping. Where else can I earn airline mileage (Delta & United Airlines) from? Many thanks for answering!

I think some utility companies will let you pay with credit cards, so every month when that bill comes you get miles, also if you have student loans you can see if those can be put on cc.

Depends on the airline, but it could include airline miles, hotel stays, car rentals, shopping, gas, insurance, moving costs, flowers, the possibilities are almost endless. And most plans are widening the range of possibilities every year. Good luck!