I have travelled the world and no where is quite like new york!
I have been 3 times, once in 1999 and twice last year.
For cheap flight look on airline network, google them and you will find it. For a good hotel, reasonably priced in a good location, try the wolcott, you too will find this by googling its name. Its on 33rd and 5th avenue, pretty much next to the empire state. I stayed in this hotel the 2 times I went in 2005. The first time I went to NYC, I was lucky enough to be living in America (those were the days) and therefore had contacts and stayed with friends in the very trendy east village.
I am so jealous. I love new york.It buzzes all the time! Last year I took my boyfriend and then went with my parents a few months after, they loved it too. I was planning to go for my 30th in June next year, but baby has put a stop to that!
I like the hotel wolcott because it is in midtown, thereofre nowhere is difficult to get to, or too far away.
I also find it easier flying into JFK instead of Newark and the taxis are cheaper into town (dont even think about using the bus they put on, it takes longer and for 2 people costs the same as a taxi.)
You shouldnt need any vaccinations for America, just make sure your tetanus etc is up to date. Make sure you have good travel insurance though, I have experienced American hospitals and they are far from cheap!
I have used both the subway and taxis. The yellow taxis are inexpensive,espacially compared to Leeds or London taxis. However, the subway isnt scary, it can be difficult to figure out where the trains are going though because some have a number and some a letter.It is something you should do once though!
Let me know if you need any further advice or recommendations.