We present ground-state calculations for laterally coupled quantum dots containing two, four, and eight electrons. As our emphasis is on spin effects our results are obtained by applying spin-density functional theory (SDFT). By varying the distance between the centers of the coupled quantum dots, the transition from the weak- to strong-coupling situation is realized. For the two-electron system we also apply the Heitler-London approximation and analytical concepts to check the reliability of SDFT calculations in this case. In addition we discuss the features of the Coulomb staircase of laterally coupled quantum dots in the weak- and strong-coupling regimes in comparison to that of a circular parabolic quantum dot.