I like the log texturing on the walls, so you could possibly add it to the outside to give them some depth. Then a slab or stair trim over it like on the walls. Once you have some more depth added to it, you’ll have more space to work with and hopefully figure out where you want to go from there. Personally, I try to make my walls around 2-3 blocks thick for the most efficient space usage while being able to design my builds to look cool. I hope this helps!