Non-maaser. I bought a ticket with points for a chabad house friend. I asked him for a tax donation receipt for the full market value if the ticket was bought in cash that day. So I tend to agree with
In that case my "opinion" is that you deduct how much money you actually saved them i.e. how much they would have spent had you not donated their flights
#my$.02
On the other hand, I never thought about having to pay maaser on the value of points earned. So this is certainly food for thought. Even not giving maaser on those I earned, how about giving tzedoko lekovod enjoying redemptions.?