How do you tip staff you rarely see?

Good question. Brick Underground has previously recommended that you not ask the super or resident manager to hand out cash tips, as some staff say they distrust this method. Another tip is to put a family photo into the envelope to help connect your face to your generosity.  So what to do?  Though cash is preferred, you could combat the sticky fingers risk by writing a check and leave it with the super. And consider these suggestions offered on StreetEasy:

• Hunt down each and every staff member personally, even if it takes you until the New Year.
• Hold “tipping hours” in your apartment: Leave a note to all staff with the doorman saying “Please stop by at (day/time).”
• If your building has an online communication system that tracks deliveries, like Building Link, log in each individual envelope and ask for an email notification when the envelopes are picked up.  
• Leave it with the super. Then, when you do see those staff members, say: ‘I would have liked to give you my holiday greeting in person, but I didn't see you so I left it with the super.’ If your super is honest, you'll know by the porter's repsonse.