I use the KISS method, especially with novice tiers present.
Wingless dry fly, all the way down to 20's, all hackle type or Catskill style minus the wing, can impress even the jaded masters.
Soft hackles, vary the body and hackle used.
Rolled wing wet flies, your imagination is the only limitation.
Birds' Nest nymphs, light to dark.
Marabou streamers.
They all work, and are impressive in their simplicity.
wcglass