I am always interested in what people are using their notebooks for. I often find that many people are using multiples for different topics.
I have a Traveller's Notebook Standard size that has three inserts. I use two of the inserts as bullet journals for work / daily life logging and my future log. The third insert is a standard long-form journal that I write in mostly daily.
I have a Passport size Traveller's Notebook with two inserts that I use as a wallet. The inserts are my gaming log where I take notes while playing whatever video games I am currently playing, and the other is just for catch-all like meeting notes, a bullet journal log for on the go, lists, thoughts etc.
I have a Hobonichi that I put just a daily log in of what I did on a particular day, and I will collect business cards or stickers from places I go an tape them in on the appropriate days. I am not a scrapbooker, but I find that this creates a fun little look through my life as I occasionally go back through old journals.
I supplement all of this with digital notes and a ToDoist account. I am a producer in the video games industry and have a lot of moving parts, so going all paper just won't work for me. But I love having this hybrid setup as I tend to remember a lot more when I write things down.
How are you using your notebooks?
I use them for:
I almost entirely quit digital note-taking (I do have a blog, though). I take all my notes on good old index cards that I store in my own version of the Zettelkasten.
I have always wanted to try Clairefontaine. They are not super popular in Aus (where I am from) and I have never seen them here in Japan, but I hear that they are really nice to write in.
They are quite nice indeed—not Tomoe River Paper nice but is there anything that is?—but still great. Paper is smooth and will hold fine with most fountain pen save the wettest Medium or broader.
You may want to check if you can find the Rhodia brand instead (somehow, they're the same-ish company). They're often available in office supply stores.