If you really want to improve as a skier, the best instruction camps I know are these:
Harb Ski Systems one-week camps at Arapahoe Basin offered throughout the year. Harald Harb and his wife, Diana Rogers, employ five high-level coaches from around the country to immerse you in the PMTS system of skiing. Groups are usually about 6, split by ability as shown in a skioff. If you're not familiar with Harald, look him up on Google. Very structured, very focused instruction. Video every day. (harbskisystems.com).
Rookie Academy camps in New Zealand. Offered from the end of June through the beginning of September, a number of options are available from three-week Advanced Camps for high-level skiers to one week and half day offerings. The coaches are the some of the best from around the world (JF Ballou, Tom Gellie, Reilly McGlashan, Sebastian Michel, JF Beaulieu, Jamie Kagan, etc.). One perk is that the exchange rate is phenomenal because everything is listed in New Zealand dollars. A course advertised as $1,000 will only cost you $600 US (rookieacademy.com).
I attend both every year.