Color me surprised! Around here I doubt we could find a single building or structure of any kind within 100 miles that dates from 1880. Regardless, I am sure your friends and family will be sensitive to your desire not to ruin your floors, even if they were of recent vintage. (Your floors, I mean, not your guests 
)
I suggested slippers rather than flip-flops or sandals because of the issues those could have with stocking feet. I understand that flat soles pose no danger to your pine, but I thought asking everyone to change to slippers might make it more compelling. No one will feel put upon, no one need feel singled out, everyone alike gets a comfy pair of slippers for casual time at your house.
