Nothing, but nothing matches the energizing effect of a visit to Manhattan. It is one of my favorite places to go, sit in a cafe, and suddenly have a million things to write. Manhattan is generally thought of as expensive, but given that many of the inhabitants buy their meals good food is actually very available and not terrible expensive. Housing is the problem.
If you are looking for cheap, ThirtyThirty is my choice of places to go. It is a "tourist class" hotel. The room with have a very basic bed with very basic covers, not much else, and internet that only sometimes works. But the bathrooms are relatively new and very nice, there is an in-room safe, and I have always felt safe there. This is a midtown location: fairly sedate. Times Square is an easy walk away, but here are plenty of quiet independent cafes and a Starbucks on every block.
Directly across the street is my favorite higher end hotel, The Carlton (no relation to Ritz-Carlton). It is what I think of as classic Manhattan luxury. If one can afford a midweek trip it can even be affordable luxury: mid-week rates can be less than half weekend rates. I love the small strangely shaped rooms with luxurious bathrooms and the hallways that travel unusual curves. The restaurant was one of my favorites when it first opened, but the last time I was there it was doing more business at the bar and the service and food weren't what they had been. If one wants to throw some money at food, the special oatmeal breakfast is where to go.
Those are by far my favorite hotels, but I will grant the Hilton Times Square a grudging third place. The hotel is at the top of a building directly on Times Square. It is strangely calm after stepping off that street. The rooms are huge and the views fabulous, but it isn't very New York and it isn't very personable. I spent an evening there with severe food poisoning (acquired elsewhere and brought to Manhattan, unfortunately) and couldn't find a bellhop willing to cross the street to the pharmacy at any price. The best I was able to do was get a Rice Crispy breakfast customized with strawberries. So the luxury is only skin deep and the price is frequently horrendous.
One doesn't need to do the tourist things, New York is enough as it is. Take a long walk and see all the things that you've seen on TV a million times: Macy's, Saks, Central Park. Sit in a cafe and read a book. But if one wants to pay, the grandest museums, the greatest shows... it's all right here.