Train
Amtrak will bring you right into Mystic in about 2 hours and 45 minutes from Penn Station...but not all trains stop in Mystic. It may be easier to take a train to New London, which is only about a ten-minute cab ride away from Mystic.
Flight
T.F. Green Airport in Providence, Rhode Island, is the closest airport to Mystic, CT. You could also fly into Bradley (Hartford), Logan (Boston), or any of the NYC Airports and rent a car or take a train for the remainder of the journey.
Hotel
We've reserved a block of rooms at the Howard Johnson in Mystic, which is about one mile away from the seaport. The room rate will be discounted: $190 for Friday night (before tax) $225 for Saturday night (before tax) You can book for either one or both (or more!) nights at those rates. You may have to call the hotel (rather than book online) to ensure that the discount is applied; just tell them you're with the Longa/Fortier wedding.
Hotel
We stayed at the Hilton one night in the off season and it was extremely pleasant. It's a slightly less budget-friendly option than the Howard Johnson, but perhaps a bit more luxurious.
Hotel
The Hyatt is another higher-end hotel option, conveniently located near the Howard Johnson and the Hilton.
Hotel
This place is on the smaller side and may book fast, but it's very quaint and right downtown--easy walking distance from pretty much everything.