I figure maybe I'm missing out on a great feature since up till now I rarely resort to using .sim files when caching out simulations.

Instead mostly use .bgeo.sc and .vdb for vdb files.

Does anyone else regularly use .sim files for caching? If so, could you describe your caching workflow in some detail?

.sim files are deathly huge - check out checkpoints. where you write out .sim every 25 frames or so.

That is very useful! I too have been writing out bgeo.sc and wondering when to use .sim as they seem so big.