I've taken a number of lessons at DV and always had a great experience. Instructor I liked the best was Nancy Rainey - she did a great job for me as well as my daughters. We always did private, full day lessons.
I also did Max 4 group lessons several times. Much cheaper of course but it's really difficult for the resort to put similarly skilled (or unskilled) skiers together. Seems like I was either bored or scared for my life!!!
Call DV and ask for Nancy!!