I am not sure if the Sapphire card works like the Platinum card or not. I know with the Platinum card you have to select an airline, then I believe you get credited for the 1st $200 you get charged by that airline.
If I had the Platinum and had United as the selected airline then the charge incurred to sit up front should be credited.
Again, not sure if the Sapphire credits ANY airline charges for the first $300 or if you need to select just one airline.
Even though I know the first year would basically be free after $300 credit, $100 towards G.E. and the Priority Pass (Standard Priority Pass annual fee is $99). Its hard to pay the annual fee.
Still trying to figure out if I can come up with $4000 in 3 months for the mileage, then maybe give it a try.