  To explain their observed radii, we present theoretical radius-age
trajectories for the extrasolar giant planets (EGPs) TrES-4, XO-3b, and
HAT-P-1b. We factor in variations in atmospheric opacity, the presence of an
inner heavy-element core, and possible heating due to orbital tidal
dissipation. A small, yet non-zero, degree of core heating is needed to explain
the observed radius of TrES-4, unless its atmospheric opacity is significantly
larger than a value equivalent to that at 10$\times$solar metallicity with
equilibrium molecular abundances. This heating rate is reasonable, and
corresponds for an energy dissipation parameter ($Q_p$) of $\sim10^{3.8}$ to an
eccentricity of $\sim$0.01, assuming 3$\times$solar atmospheric opacity and a
heavy-element core of $M_c = 30$ $M_{\oplus}$. For XO-3b, which has an observed
orbital eccentricity of 0.26, we show that tidal heating needs to be taken into
account to explain its observed radius. Furthermore, we reexamine the core mass
needed for HAT-P-1b in light of new measurements and find that it now generally
follows the correlation between stellar metallicity and core mass suggested
recently. Given various core heating rates, theoretical grids and fitting
formulae for a giant planet's equilibrium radius and equilibration timescale
are provided for planet masses $M_p=$ 0.5, 1.0, and 1.5 $M_J$ with $a =$
0.02-0.06 AU, orbiting a G2V star. When the equilibration timescale is much
shorter than that of tidal heating variation, the ``effective age'' of the
planet is shortened, resulting in evolutionary trajectories more like those of
younger EGPs. Motivated by the work of \citet{jackson08a,jackson08b}, we
suggest that this effect could indeed be important in better explaining some
observed transit radii.
