My first brooder was a large wire dog crate, lined with cardboard on the inside to prevent drafts. Since I had lined the floor with paper towels, I had placed a few segments of 2"X4"s, anywhere from 6"-12" long to help hold down the paper towels. I noticed right away that some of the chicks seemed to like to "roost" up on the 2"X4"s, especially those that were closer to the heat lamp. When I tuned a segment of 2"X4" on its side, and braced it with another one to keep it from falling over, I always had chicks up on top.
As they got a bit older (a few weeks maybe), I poked two holes into the cardboard on opposite sides of the crate, maybe 5 or 6 inches off the floor and poked a broom handle through the holes. Very quickly the chicks were using the roosts at night. During the final weeks before they were moved outside to the coop I put in a second roost that was about a foot off the floor and that became the favorite.
I just received 35 three day old "Freedom Rangers" on Friday, and started putting the 2"X4" segments on the bottom of their much larger brooder and am seeing that the wood generally has one or two chicks perched on top. So, I guess they enjoy some elevation or change in scenery right out of the shipping crate.