Skyline Divide Trail
Skyline Divide offers spectacular 360-degree views of Mount Baker (Koma Kulshan) and surrounding areas that begin just two miles up the steep trail, and it's outside North Cascades National Park so dogs are allowed. For info on how to get there see Washington Trails Association: Skyline Divide.
We've taken the dogs up there a couple of times, and all the photos below are from the first three miles of the trail. The views get more breathtaking further up the trail, so we need to get back and check that out soon.