All you have to do is create groups in your Address Book (which I already had).  If you don’t know how to do this, it is very simple.  In your Address Book, just click the plus sign at the bottom left to add a new group.  Name it whatever you would like, ‘Family’ for example.  Then you can go through your contacts and simply drag the contacts that pertain to that group over on top of the group name and drop them.  You will see a plus sign designating that that contact is being added to that group.  Now, if you click on that group name, you will see a list of all the contacts in that group.

Now, the mail part.  In Apple Mail, there is the ‘address book’ icon along the top toolbar (I think it is there by default, but if not, you can go to View > Customize Toolbar and drag the icon to your toolbar), click on that icon and it will bring up a small pop-up of your address book.  Rather than clicking on someone’s name, you simply just double click on a group and Mail will load everyone in that group into the To: line of your message.  It’s as simple as that!

The emails are all separated out too, allowing you to easily go through and remove anyone should you wish not to include them in your email message.

As I said, I feel dumb for not knowing this before, but I hope that others may find this tip helpful!