I'm a little late to the party, but I'll chime in with info on the Washington Coast.
For the core beaches in the northwest part of the state (First, Second, Rialto, and Ruby) as well as the Hoh Rainforest your best bet is to use Forks, WA, as your base. The Olympic Suites Inn
is a good place to stay and the Forks Coffee Shop is the only place in town worth eating at.
At First Beach an interesting walk is to the left, all the way down to the end where you'll find some rock formations
when the tide is low.
At Second Beach there's several options with sea stacks, although they aren't nearly as impressive as the ones in Oregon. It's a 20 minute hike each way to get there, but still worth it, and this is my favourite beach in the area. The sand mixes with water runoff from up the hill and can make for some interesting patterns
. Both First and Second beach are 20-30 minute drive from Forks proper, as they are on a road off of US-101. Make sure to account for that when trying to get there for sunset.
I've never really understood the allure of Rialto Beach, but if you slap a lensbaby on your camera anything is possible
Ruby Beach is another location that I've never really figured out, only ever getting one photo
I was happy with. Still, since it's an easy stop, it's worth going.
The Hoh Rainforest is pretty but hard to photograph. The understory in the forests on the coast is so messy it makes it hard to come up with good compositions. Make sure to keep an eye out for pleasing compositions on the road into the rainforest. I actually have better luck getting good photos
outside the actual park.
For all these locations timing the tides is key. Low tide at sunset is MONEY. Use http://saltwatertides.com/
to figure out when the tides and sunset sync up.
And of course if you're swinging through the Seattle area stop in and say hi