Charged particle motion in the guiding center approximation is analyzed for models of the Jovian and Saturnian magnetospheric magnetic fields based on Voyager magnetometer observations. Field lines are traced and shown to exhibit the previously recognized (Connerney et al., 1981a, b) distention that arises from azimuthally circulating magnetospheric currents. The spatial dependences of the guiding center bounce period and azimuthal drift rate are investigated for the model fields. The bounce period may be shorter or longer by a factor of 1--3 than in the field of the planetary dipole alone depending on whether a particle mirrors close to the magnetic equator and experience predominantly an enhanced mirror force or at high latitude and is affected principally by the extended length of the field line. Nondipolar effects in the gradient-curvature drift rate are most important at the equator and affect particles with all mirror latitudes. The effect is a factor of 10--15 for Jupiter with its strong magnetodisc current and 1--2 for Saturn with its more moderate ring current. Limits of adiabaticity are discussed and are shown to occur at quite modest kinetic energies for protons and heavier ions.