I am looking for a keeper card (pls correct my terminology here) or card that I can keep not necessarily use much. But would give some decent benefits or perks. I don't mind having little annual fees (<$100), if the benefits or perks compensates it.
What I am looking for is a card that by having it or using it will give you a good discount on purchases/access to lounges / get a free or upgraded stay an hotel or in flight. A card that I can only use once a while to keep it active.
I know about the Chase IHG / Marriott or Hyatt cards., which give a free night on the anniversary. Are these the only keeper cards or are there more like these.
Any suggestions?

Note: I already have CSP.