Just finished an excellent clinic at Northstar with NASTC. 3 full days of skill-building, tech-talks, video analysis, etc.
We had Chris Fellows and Kim Mann (she can rip too!) as the instructors with a fairly small group size (it seems they keep it to a max of 6 per instructor; we were way below that). Had a diverse group of participants including some instructors (one L3 and one L2).
Very nice structured progression starting from basics but building up very quickly. I liked that fact that even though it was a group clinic they were able to spend a fair amount of time working with each of the skiers individually. We skied together as a large group and also split up into two smaller groups. Skiing with both instructors also helped in getting different takes on the same topic (although both were very coordinated in their approach). We also skiied quite hard despite the instruction and drills (I was surprised when I looked at my vertical for the 3 days).
$ wise some might think it to be slightly on the high side but I thought it was money well spent. I would highly recommend putting it on your shortlist if you are looking for a technical (yet fun) clinic for skill development with high-level coaches.
Unfortunately for my wallet (and probably marital peace) I have already started eyeing some of their other clinics ..