I just found this and thought it was kind of neat. It's a page in your actual Delta account profile that tracks how much money your Delta card has saved you and how many miles you have accumulated with it. I've already saved a little north of $400 for the year on my Amex Delta Platinum so it has definitely paid for itself and this makes it pretty easy to make that calculation when the AF comes due.
You can find it by logging into the Delta website and then go to your profile (My Delta) page and then click the "View My SkyMiles" link and then there is a small section on the bottom right that says "SkyMiles Credit Card Rewards" that you can click on. It breaks it down all in very simple terms.
Just thought I'd share!
Apparently I have saved a big fat zero. lol. But then again, 20% inflight saving would have been 80% inflight spending....
I've questioned the usefulness of that page since they launched it last year. Direct link is here if anyone needs it: https://www.delta.com/acctactvty/loadSMCCBenefits.action
The Miles Boost progress meters at the top say they're updated monthly. Technically, that's true, but the numbers are behind a few statements. Mine updated at some point this month to my actual numbers from the 02 SEP statement. Checked bags show $50 for 2018 on this card, but $0 this year so I guess the free checked bags for international flights, First Class passengers, and Medallion members gets counted first. Certainly have used SkyClub at least 2 dozen times this year, but it appears that gaining access through Amex Platinum prevents it from counting on Delta Reserve. So yeah, "$20" this year. 
It would be interesting if they actually supplied data on how many times you got an upgrade over another Medallion in the same fare class solely due to having the Delta Reserve card or for meeting the $25k MQD waiver (#3 and #5 on the hierarchal list of 6 factors used for upgrade priority).
Ouch Fortified, might be a good candidate for a downgrade then?
To be fair, most of mine was a companion pass 😁
From what everyone is reporting sounds like might need to be taken with a grain of salt. I value the Priority Boarding as $0 even though they count it $15 per, I missed that they included that.
To be fair, most of mine was a companion pass 😁
From what everyone is reporting sounds like might need to be taken with a grain of salt. I value the Priority Boarding as $0 even though they count it $15 per, I missed that they included that.
Yeah sorry for the confusion lots of responses while I was typing one out to FortifiedHM!