I would be leary with cats and a bird...
my fiances family ran a breeding bird aviary for a while.
I had 2 ferrets with JuJu and a cockatiel at that time, and the ferrets didnt much bother either of the birds, but they were smaller. not to sound mean or anything, because I am not the know-all about birds and cats, but I would not recomend getting a tiel when you have older cats. the cats are gonna be territorial. if you had the bird first I dont think it would be a problem. Or for the matter if you have a completely seperate room for the bird where the cats wont be able to get to it then I think you would be fine.
good luck! and if you have any more questions feel free to ask!!!