Is there a full day pass available for buses in San Francisco?
I know about MUNI passes but do they include just cable cars or buses also?
Yes, the day passes include all of Muni buses, from TripAdvisor:
Muni offers 1, 3, and 7 day "Visitor Passports" which allow the user to ride all forms of Muni transportation, including the cable cars, the modern and historic (F-line) streetcars, the various diesel and electric (trolley) buses for a single flat rate and from SFMTA:
A Visitor Passport can be purchased for 1, 3, or 7 consecutive days of unlimited rides on Muni, Muni Metro, historic streetcars, and cable cars. Single ride cable car tickets are also available.