You might want to check the charity you plan on giving a donation here to make sure that they are legit. This site is linked with the Better Business Bureau to stay on top of legit charities. I kow that Give checks out many charities & then donates funds that they’ve collected for up & coming local charities around the US. They seem to be pretty picky as to which charity they share their money…often choosing some of the smaller community driven ones.
For better info on how much the administrative fees cut into your donation, you might want to check out this one . This site gives more detailed info so you can see for yourself where your donations go. After researching on this site, I have stopped giving to some of the larger ones as a good chunk of the donation goes to salaries where some people make mega money & very little ever make it into those actually needing it!!!
As for donating to one charity or splittng it up, I think you should do your heart tells you to do!!! Since numerous charities have sprung up kind of everywhere with many not being legit, I have opted to donate my money to local charities that I feel a connection. We have a community group that helps to feed & clothe those who are homeless or down on their luck. A friend works there & when she finds a single mother with several children that she feels is really trying to do her best, she lets me know & then at Thanksgiving or Christmas, I take them a turkey, ham, hamburger, assorted veggies, & some assorted desserts so maybe they can have a good family dinner for the holidays. Then once I get to know them better, sometimes Santa makes a visit for the children.