  Current observations indicate that the planet formation process often
produces multiple planet systems with nearly circular orbits, regular spacing,
a narrow range of inclination angles, and similar planetary masses of order
$m_{\rm p}\sim10M_\oplus$. Motivated by the observational sample, this paper
determines the tidal equilibrium states for this class of extrasolar planetary
systems. We start by considering two planet systems with fixed orbital spacing
and variable mass ratios. The basic conjecture explored in this paper is that
the planet formation process will act to distribute planetary masses in order
to achieve a minimum energy state. The resulting minimum energy configuration
--- subject to the constraint of constant angular momentum --- corresponds to
circular orbits confined to a plane, with nearly equal planetary masses (as
observed). We then generalize the treatment to include multiple planet systems,
where each adjacent pair of planets attains its (local) tidal equilibrium
state. The properties of observed planetary systems are close to those expected
from this pairwise equilibrium configuration. In contrast, observed systems do
not reside in a global minimum energy state. Both the equilibrium states of
this paper and observed multi-planet systems, with planets of nearly equal mass
on regularly spaced orbits, have an effective surface density of the form
$\sigma\propto r^{-2}$, much steeper than most disk models.
