I have been going every year for the last 6 years (except for this year because of surgery)
I have never taken classes but you can see everything in 2 days. We usually get there about opening on Friday, stay nearby that night and then spend all day Saturday. For us it is about a 2 hour drive so we eat dinner before hitting the road home Saturday evening.
If you want to take a couple of classes you could probably fill up 3 days, not sure if there is enough for 4 unless you want to take a lot of classes.
When it gets close, we ought to set up a meeting day and time for board members attending.