Internal Energy vs Enthalpy
Trying to figure out a good intuitive physical interpretation of enthalpy has caused thermodynamics student over the last couple of centuries to waste huge amount of their valuable time (in my judgment).  The really fundamental physical quantity is internal energy U, not enthalpy, and its physical interpretation is simple and straightforward.  I regard enthalpy as just a convenient function to work with in solving many types of physical problems.  If the function enthalpy had never been invented, we would still be able to solve these problems, but the results would not be as concise.