Recognition should be visible and tangible. Something that can be displayed with pride - like a certificate, a desk set, a note pad, a photograph, or a school coffee mug. Recognition should be personalized. All notes and invitations should be signed by one or more students on behalf of the group.
Hand write rather than just computerize.
Deliver the recognition in person rather than using the school mail boxes. Thank you and holiday notes should always let the recipient know that the note was written especially for them. A quick remembrance of something they did or said.