It is common for Douglas-fir in the same stand to vary in their appearance, even when they are all generally healthy. Some of this is genetic and other factors such as soils and various minor afflictions can change the appearance and branching habit of individual trees. It is also common for scattered individual trees to decline due to issues such as drought, insects, or diseases, while the stand as a whole remains healthy. 

To assess the overall health of your tree(s), start by looking at the tree crown (all the foliage on the tree), focusing on the top 1/2 to 1/3 of the crown. Lower branches and foliage often decline due to shade and perhaps poor airflow that makes foliage more susceptible to various needle fungi.

If the top part of the crown has lush, dense foliage, that is a sign that the tree is still healthy overall. The vigor and amount of new foliage each growing season is another indicator. Lush new growth on the top part of the crown indicates good health.

With the above in mind, take another look at your trees and see what you think. There are other diagnostic attributes of stems, branches, bark, roots, etc., but looking at the crowns is the first thing.