Night Time settings, Nikon D90 (New York)?

I'm going to New york with some friends and we got a Nikon D90. What settings might be cool to use without a tripod? Can we use flash to get a cool effect?

All of what I'm going to write is considering the shot will be at night with the city in the back ground.

Not without a tripod - sorry. What I'm about to describe is called night portrait but it does require a tripod because your shutter will be open as in a time exposure. If the camera moves at all you'll only get blur.

Okay, night portrait. First, as I mentioned, a tripod. Second, set your shutter to 1-second and let the camera decide the aperture. Pop your flash. Third, set your camera to its 10-second timer.
The reason for this is if your camera moves, even with you pressing the shutter release, you'll get blur.

Once that's done, do your half press with your focus point over one of your friends faces. Then re frame the shot without releasing the half press. Once you've got the frame and your tripod is locked, press your shutter release.

It's also very important to remind your friends that they can't move while the shutter is open or they will blur. Then, what I usually do is, count them down as the counter goes. At about 3-seconds I'll shout "blink" so they won't blink while the shutter is open and wala.

If you do this right and it may take several tries, this is the kind of result you'll get. Keep in mind
I shot this on a very dark night and you can see the result. Also my model, my grand daughter,
understood her part, pose and keep still while the shutter is open.

Should you want to discuss this kind of shot further: jimmya43@cox.net