Add more variants to give planks more of a building purpose, but these also could be used to substitute for planks for fuel or tools.
Clapboard: Made with 6 slabs in top and bottom rows and are planks, but continuous planks, stairs/slabs
Vertical Planks and Clapboard - Made with 3 blocks vertically, and no stairs/slabs
Panels: similar to polished stone and made with a sawmill if it is added.
Carved - chiseled variant for planks, made with 2 slabs.
Doors of each pattern for each wood type: Use a new sawmill block.
1. Use Quark mod for bookshelves. ladders or chests if not added to vanilla.
2. Use Mccaw's doors for more door patterns if not adcded.
3. Sawmill could be new block to make all of these.
4. Mix different planks and stuff for plain old classic oak doors/trapdoors