  The advanced versions of the LIGO and Virgo ground-based gravitational-wave
detectors are expected to operate from three sites: Hanford, Livingston, and
Cascina. Recent proposals have been made to place a fourth site in Australia or
India; and there is the possibility of using the Large Cryogenic Gravitational
Wave Telescope in Japan to further extend the network. Using Bayesian
parameter-estimation analyses of simulated gravitational-wave signals from a
range of coalescing-binary locations and orientations at fixed distance or
signal-to-noise ratio, we study the improvement in parameter estimation for the
proposed networks. We find that a fourth detector site can break degeneracies
in several parameters; in particular, the localization of the source on the sky
is improved by a factor of ~ 3--4 for an Australian site, or ~ 2.5--3.5 for an
Indian site, with more modest improvements in distance and binary inclination
estimates. This enhanced ability to localize sources on the sky will be crucial
in any search for electromagnetic counterparts to detected gravitational-wave
signals.
