GB-I've never ridden on any of that stuff up to the Delaware river, I am however a bit familiar with some of the highways going through Bucks as we had looked for a house up there years back, they do get trafficky at rush hour, but Doylestown and New Hope are very nice.
From New Hope up through NJ would probably be okay until you get a bit closer to the city. I think I have the route going up through Metuchen, NJ where I used to live, so I'm familiar with that area. I have it going to Newark following the Adventure Cycling route-I think and then taking the PATH into the city (bikes allowed). The GW bridge would be cool and I do believe it has a bike lane but haven't mapped how to get up there. Probably more enjoyable to do it as a two day ride. I have to be in NY on Nov 10th for an illustration art judging so would need to be in NY on the 9th, a Wednesday. So not sure about doing this then, but would be cool to get it on the radar.