In our neighborhood in Queens the standard is that the nanny gets paid their salary every week (and more if they work extra hours), whether the family is on vacation, she is sick, there's a holiday in the week, etc. We pay our nanny 2 weeks paid vacation in addition to paying her during our vacations, and a bonus at xmas.
If I had to do it over, I would do 2 weeks paid vacation, but one week of her choosing and one week of our choosing (when we are on vacation also). Luckily our nanny doesn't usually take more than one week of her choosing anyway, and then we usually go on vacation for about 2 wks during the year which we obviously pay her for too.
Our nanny recently got a bad cold and came to work anyway b/c my husband was out of town and she knew I needed to go to work. As a result, both kids got sick for 2 weeks, so I'm wishing I had just told her to stay home! We give her a week paid sick time.
I agree with the other postings that you treat your nanny well regardless of whether she is an immigrant, whether she's documented, regardless of ethnic background etc. She a human being taking care of the most precious things in your life, if she's not happy, how do you think she's treating your kids?