I've never taken a week long vacation without my kids. But my husband and I have taken a weekend away (1 or 2 nights) here and there throughout our 22 year marriage where the kids have stayed with Grandma and Grandpa. We average maybe about 2-3 weekends a year now and maybe one a year or less when the children were very young. We feel this is very important for our marriage. One day our children are no longer going to be living with us and I don't want to look at that man I married and be like "who the heck are you?!"
We have been to marriage conferences like the Family Life Weekend to Remember (highly recommend for any married or engaged couple, btw
) or we've gone to a local hotel just to have time to be a couple. With 3 kids and 2 dogs, we really need to do this as well as occassional date nights so that we are reminded that we are a couple, not just parents, and so we stay connected.
So, I really don't have anything against parents wanting to take time to be alone with their spouse. They are really doing something that is good for thier marriages, IMHO.