As others have mentioned the bugs will be gone around the end of August. You will likely see moose, donkeys and horses up there for sure. Lots of spackle on the trail from the latter two. Loads of people to help if you have questions about the route also, usually.
If you're fit and used to the altitude Kings can be done pretty easily in 7-10 hours round trip. I did a solo day trip up there in late August of 2009, hitting the main summit, making a quick jaunt over to the south summit and back. Neat area, wish I had more time to hit up a few more while I was up there, though the clouds moved in fast in the p.m. Being stuck on one of those ridges during a lightning storm would be harrowing... Though the spookiest thing that happened to me that day was startling some guy's donkey, which started braying loudly near his camp at Dollar Lake at about 5:00 a.m. while heading up the trail.
Pics from that day:
Looking north at the main summit from the summit of South Kings:
Main summit upper right while on the cutoff from Gunsight Pass:
Another angle looking north from South Kings: