To be honest the thought is cool and would make me feel special but not sure mentally I could keep it going too long before I started thinking marketing ploy.
Gift cards have value and are cool because you can claim you won it or got from the company for the holidays but still kind of generic and not my favorite.
"Free" session time is not really free and would be more work for you and may be an inconvenience for him with schedules.
I think p411 membership is the front runner if they do not already have it, followed by a funny card with a generic enough message not to raise any suspicions.
If they have a pre-paid phone, minutes are always useful same with gas(fuel) cards.... other than that maybe a coffee or lunch date.
I have had two lunch dates this year, one was to subway; it was cool to chat and get away from the office...cheap and easy..I liked it.
The other was a semi sb showing me their traditional dishes...also cheap and educational as I now know that me and bitter melon are not friends.