Yikes, my grandmother and my cousin (plus three children under ten years old) have invited me, as the family 'Aruba expert' to join them on a trip there next spring. I have no idea how we will find things to do together that will appeal to all. Help!

Would you have to stay with them the whole time? If you could get some time by yourself when you want, maybe it wouldn't be so bad. Is your cousin close to you in age? If so, maybe grandma could watch the kids a few times and you both could go out and find something to do that would suit both of you.