The Oyster Run to Anacortes is the last Sunday in September this year - the 26th. In 2008 the crowd was estimated at 15 to 20 thousand so there will be lots of bikes and riders. Highway 20 is the only main road into Anacortes and it can be busy and slow on normal weekdays and weekends - so if you're in a hurry it's probably best to stay away from that area on the 26th.
There are four main routes to get up there from Everett - ferry from Mukilteo to Clinton and ride up Whidbey Island, Marine Drive past Kayak Point to Stanwood and then Pioneer Highway, I-5 and Highway 9.
The first two are the most scenic and interesting. I'm thinking the Marine Drive/Whidbey Island route and then west after Deception Pass to see if I can avoid traffic jams using the smaller roads on the west side of Anacortes.
There are other more round-about ways to get there - Highway 2 East over the Cascades and Highway 20 West would be a fun weekend. Riding up to BC and taking the ferry from Tsawwassen to Vancouver Island and the ferry back to Anacortes would be interesting but would add some time sitting in ferry lines, border crossing time and the cost of a couple of ferry rides. $27.45 for the ferry from Sidney to Anacortes and $36.60 for the ferry from Tsawwassen to Vancouver Island (it's a lot cheaper on a motorcycle than driving a car - plus you get to be the first on first off).
It would be fun to spend Saturday in the Bellingham area and ride Chuckanut Drive South on Sunday morning - through Edison and into Anacortes.
Lots of choices.