New York is a laid out on a grid. Most of the time, you will be moving directly North/South, East/West (except for the older parts of the city down by Wall Street and Greenwich village, where things still wind around upon themselves). It's important to get oriented in the city, and understand commuting times. You also need to get a sense of scale. People often ask us if they should take a taxi from the Ladies Pavilion or Strawberry Fields in Central Park to the Tavern on the Green. No, it's a simple and pleasant stroll. Central Park IS the size of Monaco - but you rarely walk the whole park. You can cross it in 10-12 minutes.
Most of the time, you will be calculating the distance up or down or East and West from the center of the city (Midtown, 42-57 street) and 5th Avenue which demarcates East and West. In many cases, it is MUCH easier and quicker to walk than to take the subway, and usually much faster to walk/subway than taking a taxi. There are many taxi jokes in NY movies, and the Die Harder movie with Bruce Willis is my favourite. They commandeer a taxi, and his partner says - "Are you crazy - how can you get across town at rush hour?" so Bruce simply drives the taxi up on the grass in Central Park and cuts through.
North/South blocks in Manhattan are very short - there are 20 of them to the mile. They are mostly numbered streets - 42nd Street, etc. The numbers increase as you go north. East/West blocks are long, so 5th Avenue to 6th Avenue takes twice as long to walk as 41st to 46th street. The algorithm to find a NY address is simple, it is found in any telephone directory, and here is one Manhattan Street locator, and here is another. Use Googlemaps for walking, and Hopstop.com for subway directions. Google now has subway directions (in beta).
UPDATE 2020! Mary has relocated to Toronto, Canada. You can find information about Canadian weddings at ElopeToronto.com I'm keeping this blog because I've been told it's very helpful for couples in New York! If you need a wedding officiant in New York or Toronto, email me at MaryBeaty (at) gmail (dot) com, and I'll try to help. Best wishes! Stay safe!