I too think they are a great way of showing appreciation for jobs well done.
I have sent them to phone res agents for extraordinary help.
Recently, a new F/A in FC had been belittled behind her back, but within her hearing, by a couple of young smarta--d suits, without any justification. She almost broke into tears when I thanked her for the service and palmed her with an SOS as I departed.
AA employees really appreciate them; and it is one way we, for whom they do so much, can reward them for going out of their way.