I have started to make my own journals for this purpose and prefer to use long stitch bindings with soft wrap around covers…. The covers protect the book without making it too heavy. Long stitch binding allows plenty of room for photos and memorabilia. This particular journal is about 6″x4″ with a suede wrap around cover. The cover is made from the sleeve of a suede jacket I found in a charity shop in Italy. And that ribbon is Nova Scotia tartan, as that is where is started my trip.
This book was a bit of an experiment… I love to mix papers, especially for a travel journal, so this book was a “test run” with various papers… Plain, lined, patterned, scrapbooking cardstock, transparencies, and even a piece of craft foam!
The papers are all roughly 6″x4″ when folded. The patterned papers are ideal for adding photos and bits and pieces that I’ve picked up as I travel… maps, bus tickets, flyers and leaflets, coasters, business cards… and a Canadian Maple leaf! 
It’s well known that I love taking photos, I only have my phone camera, occasionally I wish I had a “real camera” still, especially in the evenings/low light. I take photos of just about everything! And this beauty is my favourite for printing photos to add to my journal. This little Instax Share printer is slightly smaller than my journal… so it’s easy to travel with. I can print photos straight from my phone, and because it is a “Polaroid” printer there is still an element of magic and surprise, I’m never quite sure how each picture will turn out. 
How about you, do you keep a travel journal? What are your travel necessities that may actually be luxuries?