I for one, always build tall bases so I can place ziplines at the top. There are many ways to go up in the base: Grass Stairs, Ramps (roofs), ladders, Bounce webs, acorn stairs.
As I tend to build further up in the base upwards of 9-10 floors, it gets frustrating to bring the pallets all the way back down the stairs. I usually just start putting platforms on the outside of the tower and fall onto them, but those are not very aesthetic.
We need slides that you can make out of stems/grass; straight and curved pieces. Plus I think they could be quite fun and something to put before ziplines but early game.
Now if we had pools, could put one at the bottom...