I also like using just black ink. Lately, I've been using this Platinum Preppy extra fine for my doodling. I like how different kinds of pens and tools can sometimes give different art.
I love Kraft paper! This is my third Kraft paper sketchbook, and definitely not my last. Splashed on some acrylic paint and got to doodling with my Rotring Isograph 0.5 mm. Happiness :-)