My semester long Introduction to Drawing course had around a dozen students so the interaction level with the tutor was great. Our tutor had well planned indoor and outdoor sessions; gave us brief art history/ appreciation lectures; taught the use of specific drawing principals and skills and provided mid week emails with links to Drop-Box files full of relevant images.
A term long course will set you back around $700 - $900 which isn't cheap, but with each of the sessions being three hours long, over the eighteen week term this works out to be less than $15 per hour. That's pretty good value. A two day course is around $200.
Above all, these classes will push your artistic abilities and your expectations of yourself.