Congrats on the approval and welcome to the family!
There is no reason to cancel your discover card tho, just hold onto it. They are a great company to be in with and maybe one day they will give you a CLI, just sock drawer it and let it age if you don't wanna use it. Age will do nothing but help your scores.
Congrats and let that baby age. Use the life outta your Amex and rack up points. I have the platinum and the companion tickets pay for the AF IMO.
Congrats! It's a great card. The no charge for the first checked bag pays for the AF as well. I fly Delta a lot (unfortunately) and it has worked out well for me.