The introduction of advanced radio resource management features such as directional antennas, power control and variable data rates have been proposed to increase the performance of multihop wireless networks. In this paper we study the combined effects of adaptive rate selection and power control in Spatial Time Division Multiple Access (STDMA) networks where nodes are equipped with advanced (beamforming) antennas. In our evaluation, the rates are selected from a discrete set. To assess the optimum performance of the various techniques, joint scheduling, rate and power control is done by solving a non-linear optimization problem. The results show that variable rates schemes can significantly improve the end-to-end network throughput compared to fixed rate schemes, whereas power control adds only a limited additional gain. The latter effect becomes even more pronounced as more narrow-beam antennas are used.