Following are some cages that would be quite suitable for your cockatiel. I am a firm believer that the larger the cage the better especially if your bird is not allowed out. Remember though to be mindful of the space between the bars. Ideally you do not want the space to be larger than 1/2 inch although you can get away with 3/4 inch. The last thing you want is your little buddy getting his head stuck in the bars.
Toys for Your Cockatiel
Cockatiels are a very curious bird and they can be quite active. Having toys that they can interact with will help stimulate them both mentally and physically. It is not a good idea to fill the cage with as many toys as possible. It is much better to rotate the toys that you have. Maybe you can change the toys every week or go longer depending on the toy and if he/she is playing with it. Now toys that address their chewing instinct will have to be replaced.
Don’t give up on a toy if your bird does not seem to play with it. I have had toys that my bird totally ignored for months then all of a sudden he can’t get enough of it.