  We measure the high intensity laser propagation throughout meter-scale,
channel-guided LPAs by adjusting the length of the plasma channel on a
shot-by-shot basis, showing high quality guiding of 500 TW laser pulses over 30
cm in a hydrogen plasma of density $n_0 \approx 1 \times 10^{17} \,
\mathrm{cm^{-3}}$. We observed transverse energy transport of higher-order
modes in the first $\approx 12 \, \mathrm{cm}$ of the plasma channel, followed
by quasi-matched propagation, and the gradual, dark-current-free depletion of
laser energy to the wakefield. We quantify the laser-to-wake transfer
efficiency limitations of currently available PW-class laser systems, and
demonstrate via simulation how control over the laser mode can significantly
improve accelerated beam parameters. Using just 21.3 J of laser energy, and
triggering localized electron injection into the accelerator, we observed
electron bunches with single, quasimonoenergetic peaks, relative energy spreads
as low as 3 % and energy up to 9.2 GeV with charge extending beyond 10 GeV.
