The Eugene Celebration might be too late for your plans for next week, but I thought I'd throw it into consideration anyway. Every Saturday is our Saturday Market downtown...all locally hand crafted items, food, entertainment and fantastic people watching (with a whiff of hippie flavors in the air).
Lunch on the riverside deck at McMenamin's North Bank Restaurant is pretty nice. Both sides of the Willamette River have miles of bike paths to explore. From the top of Skinner Butte downtown you can see the whole city. And, of course, the Univ. of Oregon campus is worth a look. If the girls are into sports, they might find seeing historic Hayward Field; and, perhaps, if you are in town on one of the days they stage the all comers meets, they might like to watch or even compete.
You can also look over the Lane County website and see what else there is to do in the area and what events are on the calendar.