In soft, coarse-grained models for dense polymer liquids, harsh repulsive interactions (excluded volume) between segments are replaced by soft repulsive interactions, which are sufficient to suppress density fluctuations. These models allow to efficiently study polymer melts with an experimentally relevant invariant degree of polymerization by computer simulation. Two topics will be discussed: (i) The calculation of free energies in self-assembling systems will be illustrated by studying the interface free energy of two lamellar grains of a symmetric diblock copolymer melt with perpendicular orientation (T-junction). (ii) The softness of the segmental interactions in coarse-grained models does not guarantee non-crossability of the molecules during the course of their motion. The effect of these topological constraints, which lead to reptation dynamics in dense melts of long flexible molecules, can be mimicked by slip-links and application of slip-links to the single-chain dynamics in the disordered and lamellar phase will be discussed.