  We develop an idealized dynamical model to predict the typical properties of
outer extrasolar planetary systems, at radii beyond 5 AU. Our hypothesis is
that dynamical evolution in outer planetary systems is controlled by a
combination of planet-planet scattering and planetary interactions with an
exterior disk of small bodies ("planetesimals"). Using 5,000 long duration
N-body simulations, we follow the evolution of three planets surrounded by a 50
Earth mass primordial planetesimal disk. For large planet masses (above that of
Saturn) the influence of the disk is modest, and we recover the observed
eccentricity distribution of extrasolar planets (observed primarily at smaller
radii). We explain the observed mass dependence of the eccentricity by invoking
strong correlations between planet masses in the same system. For lower mass
planets we observe diverse dynamical behavior: strong scattering events, sudden
jumps in eccentricity due to resonance crossings, and re-circularization of
scattered low-mass planets in the disk. We present distributions of the final
eccentricity and inclination, and discuss how they vary with planet mass and
initial system architecture. We predict a transition to lower eccentricities
for low mass planets at radii where disks influence the dynamics. Radial
velocity measurements capable of detecting planets with K~5 m/s and periods in
excess of 10 years will constrain this regime. We also study the population of
resonant and non-resonant multiple planet systems. We show that, among systems
with Jupiter-mass planets that avoid close encounters, the planetesimal disk
acts as a damping mechanism that frequently populates mean motion resonances.
Resonant chains ought to be common among massive planets in outer planetary
systems.
