Hi Kelly! My colleague told me about standards-based grading, which he uses to grade student learning. It's absolutely genius. You don't grade individual assignments, but rather, you study student progress toward meeting learning goals. I suggest checking out http://activegrade.com/get-started/ and getting a good format down. It takes a little more paper than a traditional grade book, and oh boy is it tough to use with some grade book software, but it sounds like you have great intentions and will make great use of it.
I like that it accommodates multiple assessment strategies. If one student wants to write an essay and a second student wants to do a hands-on activity to show what they know about the topic, you can grade both students based on their alignment with the standards.