The Chubby Chernobyl is the most known large dry fly world wide! Olive for hoppers, Orange, Gold or Tan for Golden Stones, Olive or Purple for Skwalas... the list goes on and on. Try Red and Purple as summer time attractors or as a strike indicator for the venerable "Hopper-Copper-Dropper" setup. They have great "floatabilty" (That is a word in the "Trout Fishing Dictionary") making them perfect for hanging a dropper underneath.
One of the Best all around flies for rivers with a lot of Cutthroat trout, but works well on Rainbows and Browns too!