Excluding accommodation, we spent around £10 a day on food, then we pretty much only spent what I've listed there. I guess it's hard to give a figure for each day as it literally depended on which city you are in, what you want to visit etc.
For transport in Los Angeles, we bought a 7 day bus and metro pass for $20 to use in Hollywood, then mainly walked to places from Venice Beach (our hostel was literally just down the road from the skate park and boardwalk, we could see it all from the window in our room) and occasionally got the bus back from Santa Monica when we didn't want to walk back, which was around $1.50.
For transport in New York, we bought a 7 day subway pass for $29, which was the most expensive transport pass that we had to buy, but was definitely worth it, as our hostel was just north of Central Park, so it would have been a trek getting to downtown, and buses are a no because of all of the traffic there. The subway is really easy to get around, it takes a bit of getting used to at first as there are various trains that go in the same direction, but some are much quicker as they stop at less places. If you just grab a subway map though and just take a bit of time to get your head around it, you should be fine. If you have been on the tube in London, it's not really any different, and it's very reliable for getting around the city.