My IL's offered to take dd (4.0) on holiday with them later this month but we said no. 7 nights is too long for a first trip away, also they are going to IoW which although hardly overseas still involves a long drive and a ferry crossing if she is totally miserable and wants to come home.
What we have said is that they can have her for the weekend a few times between now and next summer and she can go with them for a week next year.
She will be staying with my Mum in August but only for a couple of nights.
In all honesty though I think I will have more of a problem with it than she will [wuss]