Did our first time hike on Little Si yesterday. It's a good choice if you're short on time or get a late start. The views are really nice for not much effort...you can see most of North Bend, Teneriffe, and Rattlesnake.
We figured there would be a lot of hikers since it was a sunny Tuesday, and there were probably 20 or so. That was OK, since we were expecting it. There was a well-marked yellow jacket nest about 2/3 of the way in, and several people were stung that day. Luckily, we ran through that part and did not encounter any until the lookout (no stings, though).
The thing that was really quite gross was the amount of dog feces and the stench and flies that go with that for the first 500 yds up the trail. Apparently, people are using the beginning of the trail as a short dog walk, without bothering to clean up after their pooches. I stepped in one pile on the way up and watched a dog owner let their dog defecate in the middle of the trail when we were on the way down.
Maybe they need a sign at the parking area reminding them that if they bring a dog they need to clean up after him!