I've already returned plenty of missing wallets. However, an entire suitcase elevates the dilemma to a whole new level.
I think I'd have to return it ... unless it was clearly a screwup by an armored car company doing a bank to bank transfer, and that the bills were real (not counterfeit), used and non-sequential (not trackable). Such things are usually insured, and wouldn't pose a catastrophic hardship on a small business or a private person ... and in that lone circumstance, I might actually be somewhat tempted for a while. Call me stupid, but even in that tempting dilemma, I think there'd be atleast a 75% chance I'd still return it.
Hey, I could always describe the terrible temptation afterwards in the inevitable good samaritan interview with the local press ... some company or wealthy individual would probably be impressed enough by my scruples to hire me to a cushy job. Hey, if I were a well to do person or corporation, those are the kind of people I'd periodically reward & elevate regularly.
Coffee or Tea ? (I love both, but my body seems to prefer the latter)