An overview is given on recent computer simulation studies of polymer adsorption and aggregation using generic coarse-grained models. The simulations are performed with Monte Carlo methods in generalized ensembles (multicanonical and parallel tempering) and analyzed from a canonical and microcanonical view. As examples polymer chains interacting with a flat patterned surface or being confined in a spherical cage will be discussed. Of particular interest is the scaling behavior of conformational transitions in dependence of the polymer's bending stiffness. Bending stiffness also  plays a key role for semiflexible polymer aggregation. Our results show that this is the distinguishing parameter that controls whether amorphous aggregates or twisted bundle-like motifs are formed.