  We present the results of a new series of global 3D relativistic
magneto-hydrodynamic (MHD) simulations of thin accretion disks around spinning
black holes. The disks have aspect ratios of $H/R\sim 0.05$ and spin parameters
$a/M=0, 0.5, 0.9$, and $0.99$. Using the ray-tracing code Pandurata, we
generate broad-band thermal spectra and polarization signatures from the MHD
simulations. We find that the simulated spectra can be well fit with a simple,
universal emissivity profile that better reproduces the behavior of the
emission from the inner disk, compared to traditional analyses carried out
using a Novikov-Thorne thin disk model. Lastly, we show how spectropolarization
observations can be used to convincingly break the spin-inclination degeneracy
well-known to the continuum fitting method of measuring black hole spin.
