The most interesting association that ROADRUNNER's post dredged up was that of keeping expired cards. In the 80's and early 90's, I had really spread out my business among the companies and belonged to five airline clubs. In the last four or five years, I have stayed with one airline and have let all the other club memberships expire. However, I kept all of those cards and have used them to get into busy clubs at busy hours more than once. The only time I threw them out is when they were redesigned.
Otherwise, I keep no expired cards and carry about a dozen in a large ticket wallet together with my passport which I carry at all times. In general tho, I ID myself when checking in with my DL and do show the status cards just in case the agent forgets to look at the screen.