If you want to have much shorter exposure and also have a good balance between the flashed foreground and light of the background, then you would need to pump up your ISO.
The downside is of course more noise. However, many people have produced very nice night pictures even at high ISO. Sometimes, high ISO is the only choice when you can't ask the subjects to freeze at all. At other times, using a very high ISO for a fast shutter speed get a sharper picture because there is some movement even in posed picture if the exposure is a second or two which is very susceptible to both camera shake (vibration by wind or vehicle etc.) and subject movement.