If I were to design an honor garden - I would first choose a structure as a focal point - that either reminded me of that person or reflected something about the persons character - like for instance a statue, large rock, a fountain, a tree or a large shrub - which then would be complimented with plants that either
contained that persons name or something that they had a strong passion for
had a particular scent that they liked or I associated with them
favorite flowers that they liked or ones that reminded me of a particular time or occasion that I was with them
or maybe - I would just choose plants and flowers that reflected that persons personality - like for example - if they were lively, outgoing and always full of fun - I would use bright lively colors or cooler gentler much paler shades - if they were the more reserved quiet type.