I like your idea best.
Leaving it to the people there has a lower probability of getting the lost funds back to the rightful owner.

We were attending a Junior Olympics meet in Cleveland one year . As we were walking out of the venue my wife noticed a Daily Planner sticking out of the cushion of a chair . She looked through it and it had a woman's drivers license in it . My wife recognized the picture because she had actually held a conversation with the woman earlier that morning .This planner basically contained that woman's whole life . License , medical Insurance cards , child's prescription ,Dr's appointment reminders , Bills , you name it .The girl at the Lost and Found desk at the venue was so disconnected that my wife refused to leave it there . She left her contact information instead . From the contents of the planner we found that the woman worked at a local Bank that was walking distance . We went there and left our information with them and they tracked her down . The woman came to our Hotel that night to retrieve the planner and was literally in tears that she got it back .

Your plan is good.