When it comes to building a TBR for the day of the readathon, I always try to mix in some shorter books so I feel like I’m making some movement on my reads. There’s nothing worse than feeling like the day has gone by and you feel your progress is lacking.
Personally, I prefer adding some graphic novels and manga to my mix of reads, but there are other options as well. I’m currently reading Witch Hat Atelier for manga and enjoying it. For graphic novels I always suggest Lumberjanes or Giant Days.
Novellas are a great way to add some short reads, maybe there’s some short stories in a favorite series you haven’t read yet that you can get free or cheap on your e-reader?
Short elementary and middle grade or even picture books with your littles (or for fun on your own) are also another option.
Whether you’re a planner or a pantser, make sure to have some short reads available at hand, they make a nice quick grab if you’re not feeling your current read or need a break from a longer book.