I ran up Little Si on Saturday, December 11. In the afternoon (2PM or so) there were very few parking spots available. I imagine in summer people are parking on the road. It's actually a pretty small parking lot considering the venue and the closeness to metropolitan areas.
I wouldn't be surprised if, in peak season (all year?), 150 people per day set foot on that trail. Fortunately, the first 300 yards of trail is steep and that probably thwarts the less fit among us.
As for the climb, at a brisk stride, I made it to the top in about 40 minutes. It provides a better view than Big Si. A good place to take a date perhaps.