It is the height of whale season in Cabo and whales are plentiful and easy to see. I was just there a little over two weeks ago and we saw A LOT of whales on both a whale watching trip and a deep sea fishing trip.
You can also enjoy the downtown area with shopping bars and restaurants. There are a multitude in the port area and just outside of it in the old downtown area.
You can also do water taxi over to Lover's Beach or go around the arch to Divorce Beach. Divorce Beach is nice but it has dangerous currents thus the name "Divorce" beach.
Just be warned that Lover's Beach is also the home to a sea lion colony and it can be a bit loud and smelly.