Cabo Pulmo is pretty remote, not much to do except dive, great diving though!
Cabo San Lucas is a pretty active, hopping place with plenty of dive operators.
We stay in the hotel zone between CSL & SJdC at the Westin Club Regina and rent a car to get around.
I was told that some country's (not to be named) fishing boats illegally fish out most of the Hammerheads, so aren't as often seen. But Gordo Banks is where I was told they could be seen, along with Mantas but the time I went last year nothing but Tuna & Jacks. In December you may see migrating Humpbacks, that's always cool.
Have fun, my wife and I really like Cabo, thinking of buying some oceanfront property somewhere on the Baja peninsula.