Phone service in NYC that makes sense

Does anyone have thoughts about a decent phone provider that won't cost too much per month? Basically, I want to use a cell phone for all my phoning needs, and would like to find a way to weed through all the options for something that makes sense economically. I need unlimited calling time, preferably a flat rate for all calls made in the US, and I'm hoping for something that doesn't have weird hidden charges. Here's what I have now: an AT&T go-phone. It's pre-paid, and costs me $3 each day that I use it. That means, if I don't use it on a certain day, it's free. As soon as someone calls me, the $3 fee kicks in, but then I can talk for an unlimited number of hours that day. It can be expensive if you use it every day, of course, but works out well if you have certain busy days when you make many calls. So far it has worked for all US calls, so I like that I can call other states for the same rate. However, if I were to use it every day, it would cost about $90 a month. Does that seem like a reasonable rate? Anyone know if I can do better than that in New York?