"The Bible of Northwest Cruising" has a chapter dedicated to the San Juan Islands. Updated yearly, which is important because marinas move their docks around, bathroom and shower facilities burn down, new restaurants open, phone numbers change, etc.
Nice diagrams and info on popular destinations. 1st Edition 2013; complements the more up-to-date Waggoner Guide.
by Don Douglass & Reanne Hemingway-Douglass. 3rd Edition Revised 2011; complements the more up-to-date Waggoner Guide.
Ports and Passes is annual tide and current tables, Puget Sound to Ketchican.
Captn Jack's is for Puget Sound, Strait of Juan de Fuca, Hood Canal, San Juan Islands. Doesn't cover Inside Passage, as Ports and Passes does.
By far the best detail of currents in the San Juans. Published by Fisheries and Oceans Canada. Buy this book once, then buy the annual "Waggoner Tables" for it, to find what pages to use what days.
By Richard Blumenthal. An interesting reference. Did you know that "Hale Passage" is named after a crew member from an early expedition that stayed after to study the native people and their language? His mother wrote "Mary had a Little Lamb"... and made Thanksgiving popular!
Rosario changed the layout of their docks in 2017: https://michelle-barto-ku7c.squarespace.com/marina-map
Here's a diagram from the Waggoner Guide, including slip numbers and power: http://waggonerguide.com/wp-content/uploads/2017/04/Rosario-marina-map.pdf
Human powered craft only camping in the San Juan Islands and beyond: https://www.wwta.org/cascadia-marine-trail-map/
From Alltrails, recommendations for favorite hikes: https://www.alltrails.com/us/washington/friday-harbor
From my cruising buddies Patrick and Natalie: a map showing good and bad cell phone coverage around the San Juan Islands. Also, their experience with cell boosters. August 2020