re: Anyone have separate Cc's for different usage?

I do.

Gas - Citi CostCo Visa: 4% back on gas (just not Costco). Only use it for gas, use other Visa inside Costco

Dining - Chase Sapphire Preferred Visa: 3x points on dining. Got it last year for the sign up bonus. Chase points is the only one that can be transferred to Hyatt I believe. Haven't decided if I will keep.

Flights/travel - Amex Delta Reserve: Mainly for Delta flights or big purchases. Only card I have that will still extend warranty on purchases.

Amazon - Chase Amazon card: 5% back on Amazon purchases. I only use this for Amazon and don't carry in wallet

Catchall - Fidelity Visa: 2% cashback on everything, no limits, no fee. For anything not covered above.

Also, I have a Amex everyday card to hold my Amex MR points but don't actively use it.