Hello Princess!
If this is simply moving the boat, then the shortest route is the best. But...
One of the most beautiful trips you could do in your life as a sailor is going down the St-Lawrence, going by Montreal, Québec City, sail up the Saguenay fjord watch the Beluga whales, coast down to Gaspé, turn right and go to the Magdalen Islands, down through Canso straight, coast to Halifax, keep going coastal to Bar Harbour Maine (the navigation might be a little tricky with the 50 foot tides but most survive!).
From there you are back in the US, just coastal sail to Boston, Cape Cod, Nantucket etc.. Go to Long Island Sound and through Hell's Gate to NY City. Stay a week at the 79th street boat basin or in a Marina in Jersey City (great view). From there getting to the Chesapeake is child's play.
Of course this is a bit longer but well worth it!
Alternately you can go directly from Lunenburg to Nantucket and "save" a week to ten days... and miss the Gulf of Maine.
All the electronic charts are on one chip nowadays, The BSB charts on a dvd for the computer are easy to get. If you need the paper charts give me a shout, I have them all.
I've done the trip (in whole or in part) half a dozen times and truly think it is worth doing, for those who think it's a rough trip. I once did it on a Tanzer 26 with a 9.9 outboard!
No matter which way you go, have a great trip, not just moving the boat!
Pierre