I would also like to add them to group based on whether they are wide or narrow as I read that this is an additional property in which they differ. I however can't find a good list that defines which diphthongs are wide and which are narrow. Can someone point me to a good resource or give himself a list?
First of all, a caveat: I'd never heard the terms "wide" and "narrow" applied to diphthongs before this question, and after some searching still haven't seen them anywhere except Wikipedia's "Diphthong" article. So I wouldn't say they're particularly standard or widespread.
But, using Wikipedia's definition, if you plot the start and end of the diphthong on an F1/F2 vowel chart (like the IPA one), the "width" is the distance between them.
Using this definition,
/aw/ are "wide", while
/ow/ are "narrow". The centering diphthongs you get in non-rhotic dialects are somewhere in the middle.