I must disagree with Parker. i have a caputal one venture visa card and get 2 miles per dollar spent.
not only are they simple to use but when i want to redeem them for a flight, i go search ticket prices for my flight, purchase best priced ticket, go to cap one websie and use the cap one purchase eraser to wipe out the cost of the flight.

last year i flew business class from Jakarta to taipei, then 4 days later on same ticket business class to Vancouver and Toronto.

all free. so my advice is research your rewards and choose something not tied to hotels, or specific place. one card for everything and use it exclusively. i can even get a check or reduce my bill.