Are you planting seedlings or cut stems?
A bunch of stuff. It's part of an NRCS contract I'm doing, and the species were recommended by them. Around 100 coyote willow poles I harvested from the fish and game land across the street, then 40 various native trees and large shrubs that I ordered from Plants of the Wild (a WA nursery for Pacific Northwest natives) as seedlings - black cottonwood, peach leaf willow, scouler willow, golden currant, and silver buffaloberry.
The coyote willow poles all have to hit the Summer water table, so the holes are just about the length of the auger, which has been the biggest pain with the rocky ground. I have to drill the hole with the 2" auger, stick in the pole, then pour in a mud slurry to ensure full soil contact. The seedlings just have to go in to cover the root system, so a much shallower hole with the 6" auger, which has been much easier to do.