Not SF specific but Tri-Tip is awesome and I know for a fact is a big tailgating tradition for many as my friends Dad makes it in the parking lot every home game.
Tri-tip is big out here. Many folks do them up as tacos or sandwiches. I really like the idea of sourdough bread stuffed with tri-tip. Or, just make up some char-siu, you can grill or smoke it, sliced and served warm, it is delicious. I did these a while back...char siu ribs
Thinking baby backs done this way would be terrific. http://www.bbq-brethren.com/forum/showthread.php?t=76491&highlight=char+siu