A baitfish pattern that you have confidence in, such as the Clouser mentioned by DoubleSpey, is killer on Coho; white/peacock angel hair in about #4 works for me.
A Flash Fly in about a size #2 is a popular choice for Alaskan Silvers as is a purple Egg Sucking Leech.
You may also want to include a few Sparkle Shrimp (pink or chartreuse in about a #4.)
Several folks have been experimenting fishing surface poppers for Silvers with great success. Including a couple in your box might provide some added excitement.