I did Whipsaw two weeks ago. No BUGS! and it was still nice and warm out
Sadly, someone took a grader (seriously) to Falcon Hill. Flattened the thing right out.
I usually to every September. Best time to go. No Bugs! But its quite dry, so the soupier parts of the trail are well... dry... unless there is a good rain before hand. Have not had that though the last few years.
Longview, WA here. I haven't been to anything on the east side, but Tahuya State Forest (near Belfair, WA) and Browns Camp (near Tillamook, OR) are a lot of fun.