Important phenomena occur during solidification at a very wide range of length scales, from atomic scale interactions at the liquid-solid interface to heat flow at the dimensions of the object. Although computational models cannot include all of these phenomena at adequate resolution, it is essential that as many length scales as possible be addressed. In the first of two example applications, we show an adaptive grid level-set method for modeling the interaction of dendritic growth fronts with biological cells. In a second example, we describe results of simulations of solidification and grain formation using the phase field crystal model. This model includes atomic-scale interactions on a coarse-grained time scale.