Can you explain how this is a 9.5% return?
Sure:
$1500 on Chase Freedom #1 before 11/23 will return $93.75 (7500 points, valued at 1.25 cents per point)
$1500 on Chase Freedom #2 before 11/23 will return $93.75 (7500 points, valued at 1.25 cents per point)
$1500 on Chase Freedom #1 after 11/23 will return $187.50 (15000 points, valued at 1.25 cents per point)
$1500 on Chase Freedom #2 after 11/23 will return $187.50 (15000 points, valued at 1.25 cents per point)
$1500 on Discover it at 10% cash back will return $150.
$93.75 + $93.75 + $187.50 + $187.50 + $150 = $712.50
$712.50 / $7500 "banked at amazon" = 9.5%
So you will have $712.50 in cash and $7500 held at Amazon.
The trick is what to do once you have $7500 sitting in an Amazon account. Obviously the longer it sits there the lower your APY return. The goal would be to drain it in under 1 year. I don't know if that is possible without simply buying stuff for the sake of buying it.
I have looked over my records and I spend about $1000/yr on Amazon. I believe if I shift some of my grocery store spending over to Amazon I can hit $1500 in 1 year. So I think I'm going to put $1500 in and get back 15000 chase points. This will give me $187.50 and I will be able to spend down the $1500 during 2016.