Reorientational relaxation measurements of dilute rigid probes in o-terphenyl and polystyrene are reported. In each matrix, the results span more than 13 decades in time and extend to below the conventional glass transition temperature. The temperature dependence of the observed rotation times is roughly proportional to viscosity divided by temperature, as predicted by the Debye-Stokes-Einstein equation. Consistent with previous work on o-terphenyl [F. Fujara, B. Geil, H. Sillescu and G. Fleischer, Z. Phys. B88 (1992) 195], it is observed that probe rotational motion has a stronger temperature dependence than probe translational diffusion at low temperatures. Using translational diffusion results from the literature, it is shown for the first time that this is also true in a polymeric glass former. These results are inconsistent with several proposed models of cooperativity near the glass transition.