Hi Tom - we stayed on a mooring at the Boston Sailing Club. For $50 a night you get a mooring and launch service -- there are no shore facilities other than a dinghy dock. But the location is fantastic, and this is a very well situated stop if you want to be in the heart of downtown Boston. You can step off the launch at the Boston Aquarium or tie up your dinghy at Rowes Wharf, and you are in short walking distance to Fanuel Hall, the Freedom Trail and all the nightlife/restaurants and tourist attractions.
This is a VERY busy spot and you should expect wakes and noise from water taxis, tour boats (including the COD ZILLA high-speed boat thrill ride), ferries, and other commercial traffic from about 7AM to 11PM. But then, you wouldn't come to Boston for solitude, would you?
Another alternative for moorings (that offers showers ashore) is the Boston Waterboat Marina. They don't have launch service but the launch at the Sailing Club doesn't operate at night, so you'd end up using your dinghy anyway. It's in the same neighborhood (on the other side of the Aquarium) and I went there to see it. It is very nicely kept up -- don't be put off by the ActiveCaptain reviews describing them as "shacks on barges" -- these are nice modern structures similar in style to large construction site office trailers. We didn't go there only because they were full (we don't usually make reservations until same day of arrival because we don't want to be tied to a schedule) so I recommend reservations ASAP once you know your arrival date -- if you want to be sure of having a spot.
The Golden Goose Market is in walking distance and they will deliver, 617-367-8134. If you want to go there to pick out your own order they will drive you back in their car, so you don't need to lug heavy bags. Wonderful service. They also have bags of ice, but if you want blocks (not cubes) they will order and have it the same day.