  Finite 't Hooft coupling corrections to multiple physical observables in
strongly coupled $N=4$ supersymmetric Yang-Mills plasma are examined, in an
attempt to assess the stability of the expansion in inverse powers of the 't
Hooft coupling $\lambda$. Observables considered include thermodynamic
quantities, transport coefficients, and quasinormal mode frequencies. Although
large $\lambda$ expansions for quasinormal mode frequencies are notably less
well behaved than the expansions of other quantities, we find that a partial
resummation of higher order corrections can significantly reduce the
sensitivity of the results to the value of $\lambda$.
