I only brought a tiny sketchbook with me on my last trip to Belgium. I knew I wouldn't have much time to sketch. I also brought tools that I don't use very often, like a Kuretake brushpen that I find hard to wield.
I sketched a good bit at Dublin airport, on the way out. I had a lot of time before my flight, and sketching helps to soothe my nerves. I'm not a nervous flyer. But I am an anxious traveller. Schedules, expectations, people everywhere, loud announcements, those are not good things for me.
I also sketched on the two evenings I was on my own at the hotel, with room service. I didn't sketch the food. I just wanted to eat. But I did enjoy sketching the salt and pepper shakers.
I also enjoyed doing tiny colour mixing dots with my Art Toolkit palette
And, strange for me, I didn't sketch at all in Brussels airport. I had lots of time. I just wasn't in the mood.