Any ideas on how to make my base less bland (working on the second btw)

You can make shelves from trapdoors and put all sorts of fun things on top of them like flowerpots or candles. Leaving some walls without windows or putting gaps between windows gives your house a little more variety and you also have more room for shelves, paintings, item frames and signs. I also prefer to use lanterns as my primary light source. I think they look way nicer than torches. Some people like to cover their floors with carpets but I personally enjoy creating different floor patterns by mixing different kinds of blocks. For example a simple checker board tiling made from deepslate bricks and deepslate blocks already looks way more interesting than a plain deepslate brick floor. If you want you can slightly mimic real life by building furniture and adding support pillars. You can also build compact farms inside your base like an auto smelter or an automatic compost. Oh and one thing that I love is building small areas designed for my pets.