If you're driving from New York, it's almost 500 miles up I-95. Around 200 miles from the Maine border. People have asked how long it takes, and I've said anywhere between 8 and 11 hours. It depends so much on traffic. We've encouraged people to not do it all in one day if they can avoid it.
You can consult the map for a graphical illustration of the route.
...But by now most people have figured out what they are doing one way or another. (There's the issue whether people should take the coastal route or take I-95 all the way, and we lean mostly to taking the interstate, unless you have lots of time. We love the coastal route, but most people don't actually have enough time to enjoy it.)
Those of you flying are coming into Bangor or Portland, mostly. From the latter, you just follow I-95 up to Bangor then turn right, and then follow the same directions we give to people flying into Bangor:
From Route 95N toward or in Bangor, take Route 395E. Follow for a few miles and take US Route 1A E toward Bar Harbor/Ellsworth. Follow 1A for about 26 miles until it becomes Route 3S and follow for about 10 miles. Stay straight onto the island and follow Route 102S/198S for about 5 miles. Continue straight on 102S for another 5 miles. Route 102 becomes Main Street in town, and Seawall Road south of town.In addition to the website, we've posted several items on travel to the wedding.