There is no place I would rather be during the last two weeks of August and perhaps the first week or so of September than on these trails. That is prime summer wildflower season for this range. I have been coming down here for about the last 25 years and it never has let me down. Some years are better than others of course, but there is always an impressive display and great variety. Much more going on than on my July visits. That's my tip: wait until at least mid August.
Here is another tip: though most folks who hike this opt to do it from the trailhead at the end of the road by Ramsey Vista Campground, I prefer to start at the trailhead across from Reef Townsite Campground. The reason is that you will pass by Old Sawmill Spring, which is truly a wonderful spot. The trail is rocky and steep at first along the old road to the spring, but the reward makes up for it. The distance is the same whichever way you choose, but you don't pass the spring if you hike from Ramsey Vista.
I was lucky enough to pick a day without storms for the hike. Everything was wet and fresh from the previous day's activity, plus I had the bonus of lots of low hanging clouds providing good shade much of the time. It was a very pleasant day for a stroll up one of my favorites!