  This paper develops a general framework for studying the effectiveness of
networks of interferometric gravitational wave detectors and then uses it to
show that enlarging the existing LIGO-VIRGO network with one or more planned or
proposed detectors in Japan (LCGT), Australia, and India brings major benefits,
including much larger detection rate increases than previously thought... I
show that there is a universal probability distribution function (pdf) for
detected SNR values, which implies that the most likely SNR value of the first
detected event will be 1.26 times the search threshold. For binary systems, I
also derive the universal pdf for detected values of the orbital inclination,
taking into account the Malmquist bias; this implies that the number of
gamma-ray bursts associated with detected binary coalescences should be 3.4
times larger than expected from just the beaming fraction of the gamma burst.
Using network antenna patterns, I propose three figures of merit that
characterize the relative performance of different networks... Adding {\em any}
new site to the planned LIGO-VIRGO network can dramatically increase, by
factors of 2 to 4, the detected event rate by allowing coherent data analysis
to reduce the spurious instrumental coincident background. Moving one of the
LIGO detectors to Australia additionally improves direction-finding by a factor
of 4 or more. Adding LCGT to the original LIGO-VIRGO network not only improves
direction-finding but will further increase the detection rate over the
extra-site gain by factors of almost 2, partly by improving the network duty
cycle... Enlarged advanced networks could look forward to detecting three to
four hundred neutron star binary coalescences per year.
