Hotel costs, DC area + NYC

We’re in the very early planning stages of a big trip to the States, and I’m trying to get a feel for the budget. I’d sure like some advice to help me figure out what to budget for hotels. The hotels in question would be in Washington, DC, and in New York City, and we’d be there sometime in January of 200X (where X=5 or 6, most likely). We need one room for four people (2 adults, 2 kids) in a hotel/motel in a safe area. The room should be clean and comfortable, but doesn’t need to be fancy; two double beds, a hot shower and a TV, and we’ll be pretty happy. We won’t have our own car so good access to public transportation is also important - we’re not averse to walking to a metro/subway stop as long as it’s a safe walk. If the hotel has a restaurant/coffee shop type place where we can get breakfast, so much the better.

How much per night should I budget for such a room? I don’t need names yet, though if you’d like to recommend a hotel I can check their current rates myself.