I love using both blue spruce and Douglas fir in my Christmas arrangements. Take care with your smaller containers, however, or they can quickly overwhelm the design.
It's better to snip off the laterals into shorter pieces and clean off the bottom stem so it is free of needles.
That still allows you to add a wonder texture and color without having too large of a piece take over the design.
Quickly insert the small laterals around all sides of the mug.