I have several Eagle itineraries, depending on other targets from posts on Tweeters, whether or not the dog needs a swim at the beach or weather limitations:
I don't think you can do all of these on one of the short winter days.
Warning: my serious birding days turn into marathons.
>From King County - North on I-5 to Highway 20,
east to 4-5 miles east of Rockport and
back west for Bayview-Edison Road for Padilla Bay and Samish Flats, - remember the Eurasion Kestrel?
then March Pt Loop to Anacortes and Washington Park,
Rosario Beach at Deception Pass State Park
West to Skagit flats or south for Whidbey Island birding

For eagles only, I like to take Rt. 530 east from Arlington all the way to Rockport, turn east on Hwy 2 - back and forth on Hwy 2.
Or take Hwy 2 from Mount Vernon east to Rockport, then add on the Skagit flats if time allows.

One Bald Eagle trip turned into an obsessive eagle counting day - sorry I don't have the date except it was the late 1990's. My husband and I picked up Patti, my BBFF (best birding friend forever) in Monroe around 7 am. We decided to to tally each eagle. We left Monroe going west on Hwy 2, turned north on Rt. 9, then took Rt 530 from Arlington, through Darrington, up to Rockport. Drove east on Hwy 20 until the road was closed, turned around and continued west back on Hwy 20 it was dark before we hit Sedro Woolley. We counted 130 eagles that day - 18 in one tree in Rockport. Immatures, matures, some feeding on salmon, some flybys, but most sitting majestically in the large evergreens and deciduous both.
Marcy D'Addio
Redmond, WA