This race was suggested by Scott. Here's his breakdown of the race:

There's a large 20-mile race within reasonable distance of NYC: the Eastern States 20 Miler -- three states, seven towns, twenty miles along the seashore from the southern tip of Maine to the suburbs just above Boston. Good timing for anyone training for a spring marathon.

http://www.easternsta...

Good places to stay, depending on whether you have a car:

• Kittery, Maine -- can walk to the start -- quiet shore town with malls
  
• Hampton, New Hampshire -- much more happening shore town, with free bus service to the start
  
• Portsmouth, NH -- a big city, but you'd need a car to get to the start
  

Travel options:

• Train or bus to Boston South Station, then there's a bus to Portsmouth, NH, from which you can do a cab to a number of very close places like Kittery or Hampton. Travel time = 7+ hours.
  
• Rent a car in NYC. Expensive but convenient. Travel time = 4:30.
  
• Train or bus to Boston, then rent a car there. Noticeably cheaper. Travel time = 5-6 hours.