You can find some day trip ideas here http://www.japanmeetings.org/planner-tools/course-detail-05.php
I always think that I should visit that chocolate factory - Shiroi Koibito, when I visit Sapporo.
My family and I really enjoyed wandering around the Hokkaido Historical Village. It's a huge property with a Meiji-era street and herring indsutry buildings and even some nice short walking trails. I remember there was either an English pamphlet or English signage in each of the buildings, as well as Japanese-speakign docents to help explain things. We had a great time.