2.Fill it in like a house and have different rooms for (going off of 1.14+ blocks) cooking (furnace, smoker, blast furnace), storage, library/cartography as examples.
3.Have a town near it (just a build, it doesn't have to have villagers or animals in it)
Just some ideas of the top of my heard or what I've done in the past. Usually these days I make a simple base with a few chests for storage, common blocks I'll need and adventure, but I used to do the other two options a fair bit with a Desert Temple renovation and town buildings around it or traps with cactus/obsidian walls more so than anything too redstone involving.
Start with a small house, dig a mine down to diamond level, build the house bigger adding rooms for storage, nether portal, wall map, enchanting, brewing potions.
Add pens for chickens, cows, pigs, and a large horse barn for all the different color combinations.
Create a large sheep pen with all 16 sheep colors.
Search for all the different colors of llamas.
Tame cats of all the different colors.
Get a few dogs.
Pick a name for your base (Burgville, Cityville, Smallville, Cityburg, etc.) and build a large sign with that name on it.
Build a giant castle from which to defend against raiders.
Create a small village, convert a couple of zombie villagers, and then breed the villagers so you can trade with them. You might want to do this in the castle so you can more easily protect them from raiders.
Map a large area, and post it on a wall. Then create a series of nether portals linking to different interesting places, like painted desert, jungle, mushroom island, forest mansion, etc.