Ideas To Make Our Home Kid-Friendly for Visiting Friends with Kids? -- Good Questions

Q: My husband and I do not yet have any kids of our own, but many of our friends and family members do. We love entertaining, and are always happy when our guests bring along their children. However, we do not regularly have accommodations or entertainment for the babies/children. We are happy to invest in some items/activities that would be appreciated by families with kids, but don't know where to start! What would be some reasonable, practical, and beneficial preparations/purchases for us to ...