As far as Girl Scouts go, the national organization, GSUSA, says this:

"The Girl Scout organization does not endorse or promote any particular philosophy or religious belief. Our movement is secular and is founded on American democratic principles, one of which is freedom of religion. Each individual decides whether she or he can meet our membership requirements, which include making the Girl Scout Promise. While we believe the motivating force in Girl Scouting is a spiritual one, we do not attempt to dictate the form of a member's worship. We believe that religious beliefs are private matters for girls and their families to address."

The Girl Scout Promise is:
On my honor, I will try
To serve God and my country
To help people at all times
And to live by the Girl Scout Law.

Regarding graces or blessings, GSUSA says this:

"The Girl Scout organization does not endorse or promote any particular philosophy or religious belief. Our movement is secular and is founded on American democratic principles, one of which is freedom of religion.

Although Girl Scouts has policies supporting religious diversity, there is no policy by Girl Scouts of the USA that prohibits or requires the saying or singing of a grace, blessing, or invocation before meals by Girl Scout members in a troop/group setting, in a resident or day camp, or at meetings, conferences, and other large events. The decision to say a grace, blessing, or invocation is made locally at the troop or group level, and should be sensitive to the spiritual beliefs of all participants."

These quotes are taken from WHAT WE STAND FOR, GSUSA, 2001.