The East Portland Community Center has an Indoor Park that runs from 10am-noon. It’s a big space with lots of things for the kids to do. There is also a matted area specifically for very little ones.
Cost is $1.25 per child, adults accompanying them get in free.
We’ve designated this an a recurring Wednesday activity for this group, so few people sign up on here, but there are almost always many dads in attendence. The Indoor Park also runs on Mondays and Fridays if you are looking for an excuse to get out of the house with your little one on those days too.