Kathy, pls see the link below for a good primer on which cards that may be best for you. However, our personal experience (over the last decade) tell us that the American Express Platinum or Starwood Preferred guest cards are very useful in building miles.points balances that are transferable to multiple air/hotel programs. However, in the last 12 months, in our view, the Chase Sapphire Reserve is the top credit card that you can put in your wallet/purse that includes earning point currency that is transferable. Moreover, using the CSR card (instead of the AMX-Platinum to pay for your cruises) is far, far more lucrative (earn much more than $300 SBC) than using the AMx-Platinum. Pls see:

https://thepointsguy.com/guide/most-valuable-transfer-partners/