Hey Tom,
...for the straight-thru, overnight run, I really like the route out of Nantucket Sound through Pollock Rip Channel and up outside of the Cape... For those doing a more extended cruise of New England, it allows one to combine and exploration of the islands, particularly Nantucket, and then head for Maine without having to backtrack to Buzzards Bay, and have your schedule so dependent upon the current at the Canal...
Going up outside can be a beautiful trip, I think you might be more likely to see better winds sooner, and for most of the way... I think an overnight makes more sense going up, as opposed to coming back down south, given the prevailing winds, the return leg is the one that usually might be a bit better broken up with some stops...
This route makes better sense heading north, however, I wouldn't necessarily recommend it headed back south, unless one was very confident of settled weather by the time you'd reach Pollock Rip... The route through the Canal is the safer one on the return...
You might make mention of Stellwagen Bank, and the value of passing thru that area in daylight, and the very likely possibility of spotting some whales... I rarely have any luck in that regard, but it's definitely one of the best whale-watching locales along the entire east coast...
Good luck with your piece, I'll look forward to seeing it...
best regards,
Jon