If you have some time before or after the celebrations, Suttle Lake is a beautiful place to spend an afternoon fishing or hanging with kids by the water. You can reserve campsites there ahead of time if you would like to spend a night. The Lodge has some great breakfast and lunch options as well! It is about 40 minutes from Loloma Lodge.
The observatory is family friendly hike on some lava flow where you have a great view of the Sisters mountains. On a clear day, you can view Mt. Washington, Mt. Jefferson, the South, North, and Middle Sister, and even see Mt. Hood, 78.5 miles to the north.