  Superconductors with low superfluid density can be described by XY models. In
such models the scale of the transition temperature T_c is largely set by the
zero temperature phase stiffness (helicity modulus), a long-wavelength property
of the system: T_c = A Upsilon(0). However, the constant A is a non-universal
number, depending on dimensionality and the degree of inhomogeneity. In this
Letter, we discuss strategies for maximizing A for 2D XY models, that is, how
to maximize the transition temperature with respect to the zero temperature,
long wavelength properties. We find that a framework type of inhomogeneity can
increase the transition temperature significantly. For comparison, we present
similar results for Ising models.
