Looks like a great plan. As long as the kids are OK with 4-5 hours on the boat all of your legs look good. Check the currents on departure day, a strong ebb in Rosario will slow you way down (hug the west side of Cypress inside Strawberry Is. for a good counter current and the east side of Orcas south of Pt. Lawrence). Sydney spit is a great anchorage and fantastic beach for the kids. Winds are really flukey this time of year, make sure you have plenty of fuel
for motoring. Have a great trip!