Your mention of an analogWrite 'class' makes me wonder whether anyone has ever created an OO equivalent of Wiring. In hindsight it seems like a pretty obvious way to go, for example with an analog input pin class extending a digital pin class and so on. (This would also force to the surface the misleading implied relationship between analog input and output pins, for example.)
A few lifetimes ago I created an OO hardware abstraction layer for a bunch of hardware modules that we were using and it worked a lot better (less code duplication, easier maintenance) than the plain old 'C' version we had been using previously.