I currently have an SPG Amex and a Merrill+ card, and I'm looking for a third.

I want a third card for two reasons: I want to have a backup card that I'll rarely/never touch besides my two everyday cards, and I want to increase my ratio of unused credit to total credit for credit score purposes.

I am not looking to churn. I'm looking for a good long-term card, and I value good customer service (and will pay a little accordingly).

My spending profile is in transition right now, but I expect to be spending quite a bit on the following in the near future: rent (can I put that on a card?), air travel, hotels, food (probably a bit more restaurants than groceries; workplace provides much of my meals), electronics; and probably in that order.

I currently put everything on SPG, and only use Merrill+ where Amex is not accepted, and I tend to stay Sheratons (Starwood) most of the time (one hotel in particular, in fact).

Now Amex, for some reason, didn't approve my credit line increase, so my secondary card will likely still be seeing some spend. Because I don't fly a particular airline frequently, I'm considering a Citi PremierPass (maybe Elite) to be my second everyday card, and pushing Merrill+ to be my don't-touch backup card.

Thoughts/feedback? (Any information that would be helpful to you that I didn't include?)

Cards with a "no preset spending limit" feature typically will not report the revolving limit. This includes VISA Signature and Mastercard World/World Elite cards, and that covers most "rewards" cards because these generate higher merchant transaction fees to fund the rewards.

Has your Merrill+ account been upgraded from Platinum Plus to Signature? Even if your physical card still states "Platinum Plus" the account may have been upgraded, and the limit is probably no longer reported.

You may need to look at Amex-network cards issued by Bank of America, Barclays or Citi to find a card that will report a limit. These cards are not issued or administered by American Express, but the charges are processed through their network rather than through Mastercard or VISA.