Since cockatiels are ground feeders in nature, a larger space gives them more room to move about. Use a grate on the bottom of the cages. I personally don't have my babies or my pet cockatiels in cages as such. I made an acrylic playground for them with lots of perches, ladders and swings and they love it. But, my breeders are all in cages.
Perches Try to provide a variety of perch sizes and materials.
Perches with varying diameters and shapes, such as branches, help exercise the feet. If a bird is using the same size perch all the time, it can cause foot problems later in life. I've found most of my birds love the cement perches and prefer them over all others. If you use natural perches, please, make sure you are using safe wood and only from trees which have never been treated. Toys Cockatiels are intellegent and can become bored.