It is a no-brainer for me.
Insurance. I have a business card and use it for all equipment purchases -- both business and home. I spilled coffee on a brand new MacAir in the UA lounge in ORD and Amex paid for a new one (almost $3K I think). Regular Amex cards pay up to $1K for this, but the Plat card pays up to $10K per incident and $50K per year. [Fortunately, we don't get near that]. But, my business partner's iPhone was stolen in KL and they paid for a new one. We have had two espresso machines that died in the extra year of warranty offered by
Amex. Again, they paid with no issues.
Premium Car Rental Protection. You pay something like $25 for the trip and you get much better car insurance. I have had a couple of small scrapes to rented cars (one real and one alleged). Amex just makes it go away (from my standpoint) and the repairs could be substantial. Plus, very inexpensive for longer trips.
Never use the concierge. Like the magazine they send Plats, the concierge thinks I want conspicuous consumption -- things that are thought to be expensive. I'm cheap. I'd like to save the money and invest it or pay for my kids' education or something forward looking. I have a wonderful Executive Assistant and she runs down stuff for me.
The lounge access is OK. Used to be better but now Priority Pass works in some places. But, I think I get Priority Pass Select from someone else and use that.
Boingo may be useful. GE/Nexus nice that they pay.
Hertz #1 Club and National whatever it is and Avis Preferred Wizard are useful, but I don't know if they aren't readily attainable elsewhere.
Tried to get a special deal that was available at Ritz-Carlton for Plat holders and don't think I did.
They did assign me a person to call with questions, but she wasn't especially helpful. When she left, I bounced around but then they tried to answer a question I had.
Never have used the 2-for-1 bus class ticket. Never made economic sense.
But, I am sure the card has paid for itself on the insurance side.