I plan to be at Big Sky towards the end of Jan and would like to attend, However I'll probably only be able to be there for one or two days. Is one or two days OK or is it an event where full attendance is required?
Unless something has changed, full registration is required. If you decide to only attend to 2 days that's your choice. The agreement with the local mountain is probably such that we can not sell daily lessons as that is cutting into the local ski school's business.
At the first ESA we tried allowing people to do 1-2 days but it disrupted the group dynamics to have a new person enter after a group had hit its stride, so our preference is to have students there for the entire four days.
I am sorry if this doesn't work with your plans, because it sounds like it would be quite convenient for you, as you're already going to be at Big Sky.
Couldn't you call in sick with an Epic case of snowflu?