1. A method of computer-aided-design of integrated circuits, the method comprising: manipulating a design database representing at least a portion of a chip having an associated physical structure, operational temperature distribution, and operational electrical performance; simulating the operational temperature distribution of at least part of the chip using thermal modeling of thermally significant features of the physical structure, the thermally significant features comprising active devices and interconnect of a die and being described by the design database; based at least in part on the simulating, selectively modifying aspects of the design database in accordance with at least one predetermined criteria; wherein the manipulating, the simulating, and the selectively modifying are at least in part via at least one processor; and wherein the simulating is in accordance with a model of the chip that is in accordance with the design database and using grid points of a grid in three coordinate dimensions, and spacing of the grid is locally variable.