Ok, the trip now has a name and dates...

Trip Name: The Long Right Turn

Official Dates: 20 July - 7 August

About the dates: Obviously, things of this nature have a bit of a soft start - it is very difficult to coordinate the arrival and meetup of several different parties arriving to different places via different transportation types.  The plan is to meet up on the evening of 20 July at a camping area near-ish to Bremerton (which is a ferry ride from Seattle).  Possibly this place: https://plus.google.com/103255841432133981476/about?gl=us&hl=en .  My group will be arriving by train into downtown on 20 July morning, and we will put our bikes together, bike five blocks, then take the ferry across, and bike the 20 miles to the first campground.  Others could fly in the day before, assemble bikes and stay overnight by the airport, then bike to Seattle, ferry, and meet us on 20 July evening.  Or, if you want/need to cut the time tight, you can try to get in and bike out on the same day.  If people have trouble getting there on 20 July (like if your bike needs to be fixed or you just get behind schedule), we can easily do a short day on 21 July to allow those people to catch up (this is one of the benefits of long rides - you actually have slack for these types of things).
  On the concluding side of the bike trip, I have the official end date as 7 August, though I suggest that people put in a slack day at the end if they can.  For example, our train out of Seattle is actually on the afternoon of 9 August.  If everyone adds in an extra day at the end (planning to leave on 9 August), that would actually give the whole group an extra day to tool around Seattle or the islands or whatever.  But I know that people are tight on time, so the official plan is to get back to Bremerton on 7 August.

On taking the train:  If people have the time, taking the train may cost about the same as (or less than) flying, when taking into account bike transport.  Most airlines are charging ~$200 per bike per direction for transporting a bike, so plan to add ~$400 to the price of a round-trip ticket if you take your bike.  I understand that REI has a really nice service where you can take your bike to any REI and pay a reasonable fee to have them pack/ship to another REI/reassemble your bike.  Cheaper than taking it on the plane, but maybe less convenient.  Amtrak will take your bike for almost nothing ($15 for a bike box, $10 handling fee).  And it is less likely to be damaged in a box (which they keep standing up in the train) than naked and manhandled by airline baggage people.  While trains are usually not very useful for travel, they are a pretty nice option for bike touring.
  We are taking the train and have already booked tickets.  We would love to have others join us - email/message me to get our dates/train numbers.  It is a three day train trip for most East coast people - one day to get to Chicago and two days ride from Chicago to downtown Seattle.  But you can get sleeper cars for pretty cheap, and your room comes with three meals a day in the dining car (actual food, metal silverware, wine/beer included).  The trains will also be going through some cool areas and feature observation cars and lots of space to hang out.  We plan to bring games and puzzles, maybe some movies, and ditch all this stuff in a locker at the Seattle train station for the ride back.
  For costs, here is our breakdown: for three of us, in regular coach seats for the overnight train from Rochester to Chicago and in a room for the long Chicago to Seattle train (and the same setup on the way back), it was $1750 total.  Flying would have cost three of us about $1600, without including the bike and other luggage fees.  So the train works out to be slightly cheaper overall, but much more convenient, and we will get a cool train trip.  Of course, this works because we don't mind spending three days to travel each way (rather than one for flying).

Very Rough Schedule: So, I am thinking of the trip as going about 60 miles/day.  If things go well, I think we will naturally go slightly faster than this.  If we end up going slower, we can just zip back towards Seattle earlier on the route than planned.  This schedule is planned so as to have the easier Olympic Peninsula part at the start of the trip.  However, if you can only come for a week or so (and can handle jumping into some harder portions), I strongly suggest the middle of the trip, meeting us in Port Townsend NW of Seattle.
  I list dates, locations, approximate distance along the route, direction from Seattle, and note if there is an easy way to bike here from Seattle (hence making it a good start/end point):
20 July - into Bremerton - 20 miles - West (good meetup/depart point)
21 July - into Elma - 80 miles - SW
27 July - into Port Townsend - 310 miles - NW (good meetup/depart point)
28 July - into Sedro-Woolley - 370 miles - North
2 August - into Ellensburg - 620 miles - East (good meetup/depart point)
4 August - into Ashford - 800 miles - S (good meetup/depart point)
6 August - into Elma - 920 miles - SW
7 August - into Bremerton - 980 miles - W (good meetup/depart point)