Bottom line: your invitation should be extended to a child both you and your child know well. You don't want any surprises. Both families should be aware and comfortable with each other's parenting styles, family dynamics, expectations and procedures. If you have more than one child, you must consider how the friends would interact with each other and with the siblings.
We decided to ask my 13-year-old niece to accompany us. It was long trip, far from home. My husband and I felt uncomfortable taking any of my daughter's friends into that situation. At age 8, there's still the prospect of homesickness. Inviting my niece alleviated comfort and familiarity concerns.
How do you make your choice a reality? Here's the first of my two rules: You must (repeat, must) discuss the idea with the parents first. It would be unintentionally cruel to invite the child and raise hopes, only to find that she's unavailable (or that his or her parents think you're too nutty to care for their child). I broached the subject with my brother first, and, soon after, I received hugs and squeals from my niece.
My brother was happy, too, because he was off the hook: our conversation had already included finances. Read about money issues on the next page.