How important are grades?

Here is my dilemma. I have 7 finals (6 classes) coming up next week and little time to study. In the remaining classes (we had a couple finals last week) I have one B, a couple of 90.5's and a few really solid A's. I am debating the merits of studying economically in these last few days of class and perhaps letting some of my A's become B's. I feel that I know the subjects well but I realize that I do not have the time to dedicate to studying to guarantee an A on any of these tests. In fact, any one of these tests on their own would merit 3-5 solid days of studying in order to get an A, especially those classes where I hold a tenuous 90%. The conflict lies in that I worked pretty hard to get the grades I've got and I would feel bad about letting any of them slip. However, time and sanity dictate that I cannot put in the time needed to ace these tests and that really all that matters is that I pass. Add to this the fact that my son has responded very well to my spending addition time with him the past two days. I know which way I am leaning but if you, dear reader, have any input I'd love to read it.