I think you should have to earn it each month, or maybe each quarter. This doesn't seem like the sort of thing that you should get to keep for a year, the way you do with airline loyalty programs, given that we're talking about a daily activity here.

Another idea: Anyone spending more than $50,000 a year or $4,000 per month on the Duetto card should get elite status comped for some period of time, no matter how much or little they spend in the store.