Cliff House reservations?
You probably would still need one on the weekends.
Upstairs at the bistro, they do not take reservations.
Downstairs, they take reservations, but they also have a bar area that has a few tables that is first-come, first-serve. The bar does not face the water, and the tables there are not by the window but are elevated so that you still can look out.
Based on the one DAT lunch I had there last week (after reading rworange's recent post on the subject), the food at Sutro's at the Cliff House is pretty good--almost a match for the view! You can make reservations on Open Table. Enjoy your visit.
Sutro's at The Cliff House
1090 Point Lobos Ave., San Francisco, CA 94121