I like buying keychains from the giftshops of museums I visit. I have ones from the Louvre, MOMA in NYC, Anthropology museum in Florence, Hermitage, etc.
Most are gold-plated metal with a design from the museum.
The MOMA one lets me remove any specific key easily, such as when I am giving my car key to a parking valet. That way the valet can't copy my house key. Being careful about theft prevention is SOOO New York and part of why I like the chain even though it is not as pretty as some of the others.
I change them around when I want to remember a particular trip.