Originally Posted by Adelphos

I present this as an option: the Amex Delta Starter pack (for those without any of these cards and with three Amex credit card slots)

Delta Gold (70,000 mile sign up bonus)
Delta Platinum (100,000 mile sign up bonus)
Delta Reserve (100,000 mile sign up bonus, 20,000 mile MQM sign up bonus)

Apply now
Spend $10,000 on Delta Gold in 2020 (get sign up bonus, miles, plus $100 delta credit)
Spend $50,000 on Delta Platinum in 2020 (get sign up bonus, miles, plus 20,000 MQM)
Spend $60,000 on Delta Reserve in 2020 (get sign up bonus, miles plus 30,000 MQM)
Fly 5,000 miles on Delta in 2020 (one NYC to LAX transcon in coach will do) in 2020
Renew all three cards in 2021 for one extra year (to get remaining sign up bonuses and companion passes)

Get:
At least 390,000 Delta miles (this assumes no bonus category spend) - value of $4,290 at 1.1 cents per mile
$100 Delta Flight Credit - value of $100
Delta Platinum Status through January 2022 - N/A
One domestic coach companion ticket - value of $250
One domestic first class companion ticket - value of $500
Delta SkyClub and Centurion Lounge Access - value of $500
Total value: $5,640 (with no value ascribed to Platinum status, which many value in the thousands)

Cost
Delta Gold Fees ($100)
Delta Platinum Fees ($250 + $250)
Delta Reserve Fees ($550 + $550)
Opportunity Cost of $120,000 of spend at 2% ($2,400)
Total Cost: $4,100