Peter - I have been through a similar thought-process myself a few times, and have always been happy I decided to go for it. It's always a great experience for both captain and crew, and is a highlight for us.
On the weather, I do check (windguru) extra-intently for that trip - if there's a significant chance of rain/squalls, or winds/gusts much above 20 knots then I'd look for another day - but otherwise go for it - don't be over-cautious. I don't really look at wave height/frequency too much - just make sure it's nothing out of the ordinary.
Not sure what you thoughts are on the route, but we've done both the North Sound and Drake Channel (Scrub) departures, in each case returning to the other. Not surprisingly, leaving from North Sound is a little more comfortable.
Have fun! We'll be out there at a similar time (last week in May).
Ben
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