What would you wear if an invitation said attire -festive?

Prior to 4 years ago our ski, biking and hiking group had its Christmas party at a country club. It was very pretty and everyone dressed up. We experienced declining membership and cost increases. So the country club became too costly. One of our members volunteered her home. Someone suggested since it was in a home some would come in jeans or something too casual. So to keep it a more dressy affair I suggested we say attire "festive". The first two years everyone dressed about the same as at the country club. Now it is getting very casual -some in jeans and sneakers. at first festive was suggested as we thought the guys would be the ones to come in jeans, etc.
Last year even some women were quite casual-