  We calculate the observable properties of the most massive high-redshift
galaxies in the hierarchical formation scenario where stellar spheroid and
supermassive black hole growth are fueled by gas-rich mergers. Combining
high-resolution hydrodynamical simulations of the hierarchical formation of a
z~6 quasar, stellar population synthesis models, template AGN spectra,
prescriptions for interstellar and intergalactic absorption, and the response
of modern telescopes, the photometric evolution of galaxies destined to host
z~6 quasars are modeled at redshifts z~4-14. These massive galaxies, with
enormous stellar masses of M_star ~10^11.5-10^12 M_sun. and star formation
rates of SFR~10^3-10^4 M_sun yr^-1 at z>~7, satisfy a variety of photometric
selection criteria based on Lyman-break techniques including V-band dropouts at
z>~5, i-band dropouts at z>~6, and z-band dropouts at z>~7. The observability
of the most massive high-redshift galaxies is assessed and compared with a wide
range of existing and future photometric surveys including SDSS, GOODS/HUDF,
NOAO WDFS, UKIDSS, the IRAC Shallow Survey, Pan-STARRS, LSST, and SNAP. Massive
stellar spheroids descended from z~6 quasars will likely be detected at z~4 by
existing surveys, but owing to their low number densities the discovery of
quasar progenitor galaxies at z>7 will likely require future surveys of large
portions of the sky (>~0.5%) at wavelengths lambda>1 micron. The detection of
rare, star-bursting, massive galaxies at redshifts z>~6 would provide support
for the hierarchical formation of the earliest quasars and characterize the
primitive star-formation histories of the most luminous elliptical galaxies.
