Let me preface this by saying this I probably not the correct way to look at this. What I do is looks at what I normally buy and see how many points it would take to get it. For example a flight from mke to dfw may cost me 320 to 350 rt. I can use aa miles and that flight would cost me 25,000 miles. So to me an aa mile is 1.3 cents. Same with SPg points I love Maui and paid 360/night. At Sheraton Maui it's 12,000 pts/night so they are worth 3 cents to me. I use these numbers when determining if I want cash bck from discover or go through the aa portal. Ex. I could use the aa portal to shop at sears and earn 4 mile/dollar or go to the discover portal and earn 6% cash back