Delta Amex Gold AND Amex Platinum
 

I am lifetime Silver and don't fly much anymore. I will fly maybe 3 domestic trips and 1 Intl in next 12 months, all leisure trips. I have the DL Amex Gold card and paid the renewal fee a couple of months ago. I just received the Amex Platinum from Ameriprise (no 1st year fee and several perks). I am trying to decide if I should keep the DL Amex.
DL Amex benefits: slightly early boarding, extra baggage allowance(or does Silver get me the extra bag?)
Amex Platinum: Lounges, Global Entry fee, Uber, some airline fees

Should I cancel the DL Amex card?

Are you sure that your Ameriprise (credit or charge?) card gets all of the benefits of the regular unaffiliated AmEx Platinum charge card? Most of the other varieties do not, but I've heard that the Mercedes Benz card is an exception.

After doing some research on this site and using "uscreditcardguide.com", it appeared to me to have everything except the 1st year fee:
$200 airline fee credit for incidentals or Gift Card
$200 Uber credits ($15 per month)
Lounges: Priority Pass Select (free 2 companions), Centurion (free 2 companions), Delta ($29 for companion), Airspace (free 2 companions)
Complimentary SPG Gold and Hilton Gold
$100 for Global ENtry or TSA Pre
Platinum Card Concierge Svc

It is a Charge card

Silver will get you a free checked bag, but if you have a Delta AMEX with Silver you can have two free checked bags.

So it comes down to the priority boarding, which is nice, but you'll have to decide if that convenience is worth $95 or not. I find it to be, though there was one time at a Delta hub where I think nearly everyone had a Delta AMEX and it really didn't matter.

I'm pretty sure the DL Amex card is unnecessary since you aren't flying regularly anymore, if you were, the MQD waiver is one of the only reason a medallion would need the Gold DL card since Silver gets you basically the same benefits. DL amex and Silver Medallion both give you Zone 1 boarding. One other reason I can think of is being able to pay with miles that the DL Amex gets you. Sometimes it's cheaper to use Pay with miles than an award ticket costs.

Honestly, I think you should apply for the DL Platinum and cancel the Gold because then at least you get one complimentary companion ticket a year which covers the annual fee for the card.