Regardless of the Federal Reserve District that distributed the bill, as of 09/2012 a 1928 $100 FRN retails for $125 to $180 depending on condition.
To clear things up, the bill was distributed through the San Francisco Federal Reserve District. There's no agency called the "San Francisco Reserve". In addition at that time all bills were printed in Washington. Different sets were (and still are) printed for each Federal Reserve District as demand warrants but there aren't separate printing facilities for each one.There's more information about its value at the Related Question.
To explain, US bills aren't printed by each Federal Reserve Bank. They're all printed at a huge plant in Washington DC (and since 1991, a second facility in Fort Worth) operated by the Bureau of Engraving and Printing. Bills for each Federal Reserve district are shipped to that district's Federal Reserve bank which then distributes the notes to the commercial and retail banks it's responsible for. For prices and more information, please see the question "What is the value of a 1929 US 20 dollar Federal Reserve Note?"
Prices as of 07/2008 From Dallas: $40.-$65. From San Francisco: $40.-$125 From any other Federal Reserve district : $25.-$35.
To clear things up, there's no "Bank of San Francisco". Your bill was printed in Washington DC for the San Francisco Federal Reserve District and was distributed through that district's bank. Please see the Related Question for more information.
There were no series letters on any 1929 US bills. You may be referring instead to the Federal Reserve District letter; "G" indicates your bill was distributed by the Chicago district. There's more information at the question "What is the value of a 1929 US 100 dollar Federal Reserve Note?"
Grover Cleveland appeared on two different $20 bills, both printed in the 1914 series. There's more information at the question "What is the value of a 1914 US 20 dollar Federal Reserve Note?" For clarity, the bill was actually printed in Washington and was distributed by the Richmond Federal Reserve district.
The large letter in the center of the deal indicates the Federal Reserve District.
It is worth as much as 60$ to 120$.
There were no series letters on any 1929-dated US bills. A large "G" indicates that the bill was distributed through the Chicago Federal Reserve District. There's more information at the question "What is the value of a 1929 US 5 dollar Federal Reserve Note?"
To clear things up, the bill wasn't made in Chicago. It was printed in Washington for distribution through the Chicago Federal Reserve District. Please see the question "What is the value of a 1934 A 10 dollar Federal Reserve Note?" for values and other information.
It depends on what letter, if any, is next to the date. A 1928 C bill from the Cleveland* Federal Reserve District is quite valuable, with prices for a circulated bill in the $250 to $450 range as of 10/2011. Other letters are much more common; please see the Related Question for more. (*) To explain, there's no "Federal Reserve of Ohio". It's actually the Fourth Federal Reserve District which has its offices in Cleveland, so it's generally referred to as the Cleveland Federal Reserve District.
There were no series letters on any 1929 US bills. You may be referring instead to the Federal Reserve District letter; "G" indicates your bill was distributed by the Chicago district. There's more information at the question "What is the value of a 1929 US 100 dollar Federal Reserve Note?"