Great ride, my wife and I normally do it every August Long weekend. We usually go down and come up from the south, do Windy Ridge, agree that the north road out is veeerry bumpy. But great roads all around there. As August long weekend is a Monday and a work day in the US, we like to do Rainer on the Monday coming back, less traffic.
And August it should always be open, earlier in the season is hit and miss, sometimes snow keeps the road closed late into the season.