I've done Michel Pratte camps at Whistler in July, Alyeska Ski Club camps in June at Alyeska and November at Mammoth.
The Michele Pratte camp group was completely adult, and although he had a kid group running at the same time we each had our own coach and lane for training. A lot of camps are run that way. Most of them are advertised as Adult Camps or Masters Camps. Look at the Ski Racing website for a couple of advertisements.
Having done both Summer and Fall camps, the Fall camps did more for me because the season was just around the corner and the muscle (and mental) memory was still fresh. Either way, I still kept a daily journal of drills and impressions, noting conditions and anything else that may have played a factor into the success or failure of the day's training. Summer or Fall, your skiing will be positively impacted.
This season has not been kind to the PNW, so I'm curious how the Mt Hood and Blackcomb glaciers are going to be this Summer.