man, awesome NYC shots... I love cityscapes and skylines and you've got some really good ones. you should definitely be trying some of those views in HDR... with the dawn/dusk skyline shots I'd also be toying around with long exposure, it would give the water a soft look and put some motion in the sky...
HDR can be tough with people in the frame that are moving... sometimes you get them cloned which results in alot of time touching up... and when you try it, the more shots you have to blend, the less noise there will be in the final image. Noise is a major problem with 3 shot HDRs - with 5,7,9 or more it becomes less an issue.

