I'm running a trio up from Seattle. (2 solos and a double). I'll be honest with you, I dunno if I want to make the group any larger. I could stretch it to 4 bikes (maybe 5), but my experience is that groups bigger than 5 bikes get to be a problem over longer distances.
Our plan is to leave Seattle on the 18th at a reasonable hour of the morning. We're in no giant hurry.
I tend to agree with you, 2Wheels. 2 to 5 riders in a group sounds about right. Otherwise there's just too much overhead in planning and managing the ride.
Which way you going to go? I rode Hwy 20 in WA last year and that's a really nice ride. You could go out that way then up through Osoyoos to Nakusp.