Good timing. As mentioned, you'll have company.
Fly patterns are whatever you like. They're steelhead, and they're not picky. I tie a lot of marabou streamers on size 1 or 2 hooks (up to 3/0 cuz someone gave them to me) because they are easy to tie and effective. I tie in black, red, orange, pink, and purple, but I imagine any color works.
I usually stay at the Forks Motel ($55/single IIRC). There is a restaurant across the street and the ever popular breakfast diner 2 blocks north where all the guides meet. Other motels are Olympic Suites, Dew Drop Inn, and Pacific. Olympic Suites has kitchen facilities if you like to cook your own meals.
Any of the rivers that are open are good choices. Walk in access is not easy, even if you have a GPS with 7 1/2 minute Topo maps. You don't need a guide, but a guide will have a boat, and that equals access to all of the water, instead of a few walk in pools. Guides in the area include Jim Kerr, J.D. Love, and others. You can book a guide through Waters West in Port Angeles. I think John Farrar will be on the Hoh in March. If you don't hire a guide and don't have access to a boat, the GPS with Topo will be your best friend, along with a Gazeteer.
You can buy Scotch in most grocery stores, but the best selections are in smaller private liquor stores just about everywhere.
Good luck. Maybe see you out there.