  We consider the quasilocal thermodynamics of rotating black holes in
asymptotically flat and asymptotically anti de Sitter spacetimes. Using the
minimal number of intrinsic boundary counterterms inspired by the AdS/CFT
correspondence, we find that we are able to carry out an analysis of the
thermodynamics of these black holes for virtually all possible values of the
rotation parameter and cosmological constant that leave the quasilocal boundary
well-defined, going well beyond what is possible with background subtraction
methods. Specifically, we compute the quasilocal energy $E$ and angular
momentum $J$ for arbitrary values of the rotation, mass and cosmological
constant parameters for the 3+1 dimensional Kerr, Kerr-AdS black holes and 2+1
dimensional BTZ black hole. We perform a quasilocal stability analysis and find
phase behavior that is commensurate with previous analyses carried out at
infinity.
