I discuss mass-energy for volume renormalizable and asymptotically Poincaré-Einstein (APE) manifolds. Using an expansion in the Fefferman-Graham special defining function, I prove invariance of the Wang mass aspect in odd (bulk) dimensions, partially answering a question of Chrusciel and Herzlich (who proved invariance of the mass in all dimensions by other methods). I also discuss a Penrose-type inequality for static APE metrics found in work with GJ Galloway, and an application to black hole thermodynamics via the renormalized volume (or on-shell action). Finally, I list some open cases of the positive energy theorem for APE manifolds, particularly (but not exclusively) in the nonsupersymmetric setting where negative mass can arise. A long-standing conjecture is that, for spacetimes having the conformal boundary of a fixed Horowitz-Myers geon, this geon realizes a lower bound for the mass. In that context I give a limited rigidity result for the Horowitz-Myers geons.