Millimeter-wave radios have great potential of spatial interference management through its physically small but possibly electrically large antenna aperture. It is expected that the interference management becomes a major challenge after massive deployment of millimeter-wave devices. This paper therefore discusses design guidelines and an influential radio link property of two beamforming schemes for spatial coexistence at 60 GHz; conventional gain focusing and the interference alignment. The guideline is derived from an example of distributed channels in a small room. The investigation shows that, under a moderate receive signal-to-noise ratio, 1) having 2λ² antenna apertures at the Tx and Rx realizes 3 to 7 bit/s/Hz under the presence of mutual interference, 2) the gain focusing is as robust as the interference alignment, and finally, 3) inter-link correlation is a primary bottleneck in the interference alignment.