It is next to impossible. Think of an art gallery, and all that gets said by critics about the items IN the gallery, and those that are NOT IN the gallery, but should be. Just using the word "art" to describe something can easily start an argument! Find out who does the quality and style of landscaping you want, and then work with them.
Generally the same criteria you use to choose an architect, a builder, or an interior decorator. Remember that "Landscaper" is not a well defined term which makes the years in business, reputation and skill level all the more important to assess. Find out who does the quality and style of landscaping you want and then work with them.
There are many aspects of our region that differ from other parts of the country. Many people move here from either coast, Georgia, Florida, or other places that have a much milder climate, a more diverse plant selection, and better soil conditions to name a few. I will briefly comment on these and others.
Climate: The low-humidity and cold winters require hardier plants.
Soil Conditions: Ours is generally alkaline. Steep terrain and rocky soil dictate, to a large degree, design, plant selections, and prices.
Population: Our sparse population is what attracts many of us to this area of the country. A small populace impacts the price you will pay for most kinds of high quality work. The seasonal nature of landscaping, the great distances to transport materials and equipment, and the lack of a sufficient labor pool all make for higher prices than you may be accustomed to in the market you are from.