What kind of
boat are you delivering and what is its cruising speed?
Do you have crew to do it in a straight shot, or are you planning on stopping for the night in
anchorages along the way?
If you'll be stopping (and even if you're not), you'll probably be transiting the
cape cod canal. Be sure to check the
canal tide tables and plan your trip through it to go with the
current.
If it were me and I wanted to move quickly, but stop at night, I would do a long day (120miles) to P-town, the next day through the canal and a little under a hundred miles to Block Island, and the third day around a hundred to City Island. If you want a shorter first day, stop at Cape Ann (Sandy Bay, Anisquam, or Gloucester), then Cutty Hunk. If you wanted to go non-stop you're looking at about 300nm -- depending on the boat that is probably 1.5-2 days. If going non-stop I'd be inclined to go outside
Cape Cod.
Also, watch the
weather. The winds can come from any point on the
compass, but generally from the southwest that time of year. It'd be less fun motoring into the
wind the whole way, and if facing days of that I'd be inclined to either delay or do shorter days.