Completely agree about Acapulco. Even Jason Bourne would have reservations about travelling there.
With regards to Cabo vs. Puerto Vallarta.....
For the same hotel quality, Puerto Vallarta is cheaper.
The town is cuter. Downtown has been transformed in recent years with cobblestone streets, the old Cathedral, and historic architecture.
Great views of the PV bay from the hills that surround the city.
With all that said...unless I snag an incredible hotel deal in PV, I always go to Cabo.
Outside of the summer/early fall months you get a dry heat in Cabo.
The coastal Mexican cities (Mazatlan, Puerto Vallarta, Ixtapa and Acapulco) are far more humid.
There's also a very stark beauty about Cabo. It's a desert environment, and you get a very blue sea.
Cabo has a bit of a Greek island/Mediterranean Sea vibe about it.