There were over 51,000 finishers this year and you noticed it! It was like riding a wave of energy for 26.2 miles. This was my second NYC Marathon but I feel like I had a much better experience because I knew what to expect and could enjoy it. The people and the energy of the city really make this an unrivaled race. Every runner must do this at least once!

Expo: it's huge and can get crowded. We flew in early this year and made it close to opening on Thursday morning. I highly recommend doing this if you can because they had all the clothing sizes available and there were no lines. Also, there's a lot of walking involved, so arriving in NY on Saturday and heading to the expo isn't a great plan the day before the race; you'll definitely be tired for race day if you do that.
Start: I was a charity runner this year and we had a private bus from the Plaza Hotel. It wasn't much different from taking the official race bus from Bryant Park (what I did in 2013), except we were allowed to stay on the bus for several hours at the start, rather than waiting outside. We walked from the bus to the start about 90 minutes before our start time. There were no lines for security or bathrooms. There's also plenty of bathrooms in the start corrals so you have multiple opportunities.
Race: the start is pretty crowded over the bridge, but it's an uphill start for the first mile so you don't need to go fast anyway. I made up over a minute coming down the bridge in the second mile. The first half marathon is in Brooklyn, mostly a straight, relatively flat shot down 4th Ave. The crowds and music are awesome. The second bridge sends you into Queens for less than 2 miles, an area that's pretty uneventful.
Then you head onto the Queensboro Bridge. The first mile of the bridge is uphill and it sucks; this is mile 15 afterall. There's no spectators allowed on the bridge but it's nice having a bit of quiet in the middle of the race and just enjoy it with other runners and a few NYPD officers. You come downhill off the bridge and make a uturn onto 1st Ave in Manhattan at mile 16+. This part of the race is epic. The crowds are intense and you can literally see a wave of runners for miles down 1st Ave.
4th bridge sends you into the Bronx at mile 19.5 and the last bridge back into Manhattan comes around mile 21. There was a large group of spectators chanting "last damn bridge!" and it was highly entertaining. The bridges are no joke! NYC may seem flat but this is not an easy course; I usually describe it to people as "tricky". You're best not to bank time in the first half because you'll be hurting from that in the second half. Start conservative and save your energy for the second half. The last 5 miles in Manhattan are the hilliest part of the race, so be prepared!
Finish: This was my 11th road marathon and I still got very emotional at the finish. Tons of screaming fans, the course lined with the flags of all the nations represented at the race, a finishers chute that feels like you're in the Olympics. It's all amazing. The walk out of the finishers area is long, probably about a mile even if you take the poncho option. They do give you a heat sheet at the finish line regardless of your baggage option. Then you grab your medal, food, drink, pics, and head either towards baggage trucks or ponchos, depending on what you chose at registration. I HIGHLY recommend the poncho option. You have to walk much further for the baggage trucks and the ponchos are really cozy!

Post race: find a hotel or AirBnB near the Central Park. It's very difficult to get a cab or Uber after the race so being able to walk back home is a must!