My mum would be happy to mind the kids for however long but I couldn't do longer than a weekend away with hubby. I could do a few days and did two weeks in hospital but they were with him. I couldn't go overseas for the same reason as slmeone above said, I would be beside myself trying to get back if something happened. We have been overseas a few times and they have always come.
That's just me, you have to do whatever you are comfortable with and plenty of people do it all the time