Before you get too "into" notebooks here's something to consider. do you want your notebooks to have a "uniformed look" and where will they be stored? When I first started using notebooks to organize stuff....I must admit, I went a little notebook crazy. I used different notebooks I had on hand and purchased clearance ones in different colors and sizes. After a bit it started to really bug me...the way they looked on the shelf.
Currently I house most of my notebooks in my office on the shelf at the top of the desk. The other most used notebooks are in the kitchen on the recipes shelf. I have a few on the book shelf next to my desk but most of those are archival rather than used on a regular basis. The picture above shows my office notebooks. You will notice that most of them are black clear views (1 1/2 inch) Reference style. These just seem to work best for me.
I have four holiday notebooks, my Home Notebook, Budget/Finances Notebook and the three colored ones are for technical stuff about internet writing, Magical Holiday Home.com stuff, and the last one is a writer's notebook. Eventually I would like to convert them all to black clear view but being thrifty I can't stand to get rid of perfectly good notebooks! So if you are starting to use notebooks think about this personal preference before investing in them!