If you ask baseball historians who hit the most triples in a season, they will reply Chief Wilson of the Pirates, with 36 triples in 1912, because they automatically assume you are asking about the major leagues. However, if you ask for the answer to the question for all of baseball, including Negro Leagues, minor leagues, high schools, colleges, American Legion and Babe Ruth League and town ball, Cuba and Japan and Italy and all other nations, I would guess no one has ever even asked the question, much less answered it. I believe we must ask and answer such questions. My research is hopefully one small contribution towards taking a global approach to baseball research, in which all levels of competition and all nations of the world are given equal treatment.– Phil Lowry, I Don’t Care If I Ever Get Back: Marathons Lasting 20 or More Innings.
The most recent issue of SABR's The Baseball Research Journal contains an incredible work by Green Cathedrals author Phil Lowry. Spending 40 years on the project, Lowry looked at not only the major and minor leagues, but many other leagues as well.
As far as Giants marathons on Lowry’s exhaustive list, they are as follows. By the way, he mentions, “I especially treasure my “Croix de Candlestick,” earned in the Giants’ “Cave of the Winds.” And there's a photo of one on the back of the publication.
July 17, 1914, Giants 3, Pirates 1 at Forbes Field (21 innings)
Rube Marquard pitched all 21 innings.
May 31, 1964, Giants 8, Mets 6 at Shea Stadium (23 Innings)
Game Two of the famous Saturday doubleheader at Shea (longest doubleheader in the majors in the 20th Century). It was the largest crowd to date of the season (57, 037) but one has to wonder how many folks stuck around until the final out at 11:25 p.m. The Giants had a rally in the 14th when Jesus Alou singled to right and Mays walked. But Cepeda lined into a triple play. Mays played short for the 10th, 11th and 12th inning before resuming his CF duties for the rest of the game.
September 1, 1967, Giants 1, Reds 0 at Crosley Field (21 innings)
Gaylord Perry pitched the first 16 innings of this game. Five games later the Giants went 15 innings and beat Houston 3-2 at Candlestick. 8 games later the Giants lost to the Pirates 5-4 at Pittsburgh in 16 innings.
June 9, 1980, Giants 3, Phillies 1 at Veterans Stadium
This wasn’t an extra-inning game but Lowry found it to be the longest rain delay (Five hours) during one inning. At the end of the top of the fourth, rain delayed the game for an hour and 28 minutes. After Philly scored a run in the bottom of the fourth off starter John Montefusco, and made two outs, there was another rain delay of three hours and thirty-two minutes.
The Giants scored two in the eighth and one in the ninth to win 3-1. The game ended at 3:11 am.