I'm a definite starter - surprise, surprise.
Having lived in Karratha for 10 years and Broome prior to that, the
some hot weather won't bother me. I've got a commitment on 3 April, otherwise anytime either side of that date suits me.
Easter is 10/4 to 13/4. School hols commence at Easter - not sure how much traffic that would bring to the Gt Central Rd (GCR). Anzac Day holiday (Mon 27/4) marks the end of school hols.
I was on the GCR first week of May this year. Beautiful days; perhaps a touch cool at night. Was always looking to keep the fire roaring, but I tend to do that anyway.
I understand there's always a club trip planned for the June long weekend. If that's correct, it might be best to keep a gap between rides so that addicts like me can get a leave pass for every long ride happening

.
Duration? I'm flexible. Under 10 days would be a bit quick. Based on my recent experience, I'd suggest the minimums are... Perth to Laverton - say 2 days each way (there's a number of ways to go). GCR is a 2.5 day ride one way with little stopping at a modest clip. At Yalara? Group decision; maybe 2 - 3 days. Total = 11 to 12 days.
Having said all that (I
can go on a bit), my preference would be a departure date Saturday 4 April 2009, allowing a max of 14 days. Truth be known, I'll go anytime

(except 3 Apr of course).