TV's that say they are 120hz, are not 120hz. At least, they do not accept 120hz worth of information. They only taken in 60hz of info, and do some post processing to generate the extra frames. 3D Vision will not work with that.
For a 3DTV, it is often possible to use Nvidia 3DTV play, from what I hear. I believe the side by side format works best, as it will allow for 60hz gaming at their native resolution, but the image is still an upscaled image. Ultimately monitors are better for this, unless size is key for you.