I'm studying up on cruises as well. If you haven't already stumbled across it, I recommend the website
www.cruisemates.com. It's kind of a one-stop shop for helpful cruise information. Of course there are other cruise websites as well, but Cruisemates is pretty all-encompassing. Check out the "First time Cruisers" and "Family Cruising" sections, for example.
As for itineraries from various ports (NYC, for example), start at this page:
http://www.cruisemates.com/articles/itineraries/