When you say your current remote triggers don't work, I'll assume you mean the CLS system, which is and infra red system built-in to those flashes.

The Nikon CLS system, being intra-red, only works if the flashes are in the line of sight of the camera. If they are around a corner, or behind your group of people the signal will get blocked.

You can improve the reception by making sure the infra red sensor on the flash is pointing towards the camera. Turn the body of the flash so the sensor points towards the camera, and then rotate the flash head to point where you want it.

You can also buy an SU-800 controller, which goes in the camera hot shoe. It too is infra-red, but will have a bigger range than the one built into the D700 pop-up flash, if that's what you're using.

If none of that works well enough for you, then you would need to use radio triggers.

There are some recommendations here: Recommendations for Wireless Flash Triggers

With most of the basic wireless triggers you must set the flash power is manually at each flash - there is no TTL or CLS integration. There are newer models starting to come on the market that do handle TTL and allow you to control it from the transmitter on-camera. For example the Phottix Odin system, which allows you to control multiple groups of off-camera flashes.