Hotel
The Summit Grand Hotel is the closest full service hotel to all of the wedding activities. It's a great place to meet before, after and in between events. It is also walking distance to downtown Summit (which includes express trains to NYC).
Flight
Newark Airport (EWR) is a 15 minute drive away from Summit and 30-40 minutes from Midtown NYC (by car or train). It is the most convenient airport and generally best travel experience. (JFK and La Guardia are also options but generally surrounded by traffic and are further away). We would recommend Newark Airport even for those who wish to tack on a NYC leg to their trip.
Train
NJ Transit provides train service to and from New York City (including express trains from Summit). You can buy tickets and view schedules online, in the station or with the NJT "On Time" app.