I lucked out, they sent me two simultaneous 5K offers for two different cards (Plat and Open, the gold business card) and even though the T&C said I could only get one bonus per MR account, they gave me both. What I do notice is that my "minimum payment" on my statement is the amount of charges not eligible for Pay Over Time. So if I just paid the "Amount Due" I would be paying interest. Of course I don't HAVE to pay the minimum, and I don't.
I'm a total points hound (for reasons not worth going into, points have an actual value to me of 2 cents each), so I grab all I can.