You will get a million answers, it's a fantastic trip, but Sept '14 we did a week long trip too. Not necessarily in this order, I'm not looking at a map, but we did Sucia, Friday Harbor, Rosario, Tod Inlet, Pender Island, Roche Harbor, and our last night in Chukanut Bay before returning the charter boat to Bellingham. That might sound like a lot but it felt like a very leisurely trip, it's all relatively close together. We had a blast, beautiful every day.
You'll get a million different opinions too of course, but my two cents, for whatever it's worth: Rosario is a charming little village, beautiful resort building and we had a fantastic dinner there, but it's a tiny place, only worth a day and one night in my opinion. Same with Roche (lots of people have a disdain for Roche Harbor I know because lots of richies go there with giant boats and it feels snobby, but oh well. My clearest memory of Roche Harbor was the obnoxious U.S. Customs guy processing us back into the US). Friday Harbor was fun, lots to do there, could easily spend two days there, but yeah, it's very touristy. Still beautiful and fun though. Make sure you hit the cheese shop. Excellent supermarket in Friday Harbor. Sucia was beautiful too, but it's a park of course, not a town or village. I'm glad we did it, and we hiked the trails, spectacular, but I guess it's a preference thing. We love little waterfront towns and discovering restaurants and seafood and marinas and people, but Sucia is really a hike through the woods, a backpackers' dream.
My two favorite places though were Poets Cove/Pender Island, and Tod Inlet. Both of those places were just magic. They were exactly what you hope for on a sailing trip. At Tod Inlet we stayed at the very top of the inlet, as far up as we could go. Perfect silence, eagles, seals slipping past the boat in the morning mist, and you can take a pretty easy walk to Buchart Gardens from a little Parks Canada dock/shed on one side of the inlet. Serenity like you wouldn't believe. Even if you're not a garden and flower person, Buchart Gardens will blow you away. And then the resort at Poet's Cove on Pender was another magical place. I see it gets lots of terrible reviews on TripAdvisor but when we were there it was paradise. Excellent showers and facilities, easy check-in into Canada, nice docks, posh resort building, fantastic meal at the restaurant on the outdoor patio, good drinks. On a chilly night we swam in the warm pool overlooking the harbor for hours under the stars with a few other boaters who were great fun. Yes, they may have management problems, but even then -- for example, the barrista never showed up to open the coffee shop in the morning, so the resort manager on duty opened the coffee shop for us and gave us the run of it ourselves, no charge. It was hilarious.
You'll have a great time.