Heaps of interest in SF. The Tenderloin area is one ;-> (slightly kidding).
A great way to see great views of SF from another perspective (& cheap) is to do a ferry to Sausalito & back. Also if you have the use of a car (day rentals are always cheap) is to do both Golden Gate & Oakland Bay Bridge. Great views & photo opps. Also Coit Tower offers fantastic panoramic views over SF:
Coit Tower, San Francisco
Big Sur...well where does one start?
Pfeiffer State Park:
Pfeiffer Big Sur SP
Staying at the Deetjens Big Sur Inn in Ventana is an experience, great food too (not cheap).
The Ventana Campground in Post Canyon is also worth consideration:
Ventana Campground, Big Sur Camping
And for something a little different, a dip & maybe a massage (the massage is not cheap) at the Big Sur Hot Springs at Esalen Institute. Fantastic coast views from the bath house which is perched on a cliffside.
Swimware is optional :->
Esalen: The Place - "The Hot Springs"
Enjoy