P.P.
How long has it been since your parents saw the kids? If its been a long time, I would say take the kids. I work with a lady who has 5 year old twin girls and they have taken the children to France once a year since shortly after their birth. (Her husband is French.)
However, if they have seen them recently and since you have grandparents willing to watch them, I say go on your own. My husband and I took a week and went on an Alaskan cruise, leaving my son with my parents. We had a blast and it was so nice to reconnect as husband and wife, instead of as father and mother. We now take shorter trips alone so that we can enjoy the things that made us want to get married in the first place. Yes, we miss the kids. But as a couple, it has really helped us.