I am veering off on a side note about indoor house cats who don't get along, or have aggression issues, because I had this problem in my house for 2 years! I just came across this link that really spells it out. I have never seen this laid out so simply, clearly and concisely. Get your cats up high! It solved a 2-year aggression problem in my house virtually overnight! Get rid of the baby gate, the separate rooms, don't worry so much about the Feliway, and put the jungle gym in an area all the cats like to be in. I've got one that is 6'+ and all 5 of our fuzzies hang out on it in comfort and confidence. They swish their tails while up there, they just love it. It wasn't my dream living room to have this massive structure in there, but if we want harmonious feline companions, we have to give a little!
There are only 3 cats pictured here, but I've seen 4 of my 5 up there all at one time, including the former aggressor. Height brings territory security, which is the cause of most aggression in cats. Shy ones are happier and out more, aggressive ones feel more relaxed and in charge without needing to charge around like maniacs. Our former aggressor, Cricket, is pictured on the lower right, happy as a clam and not bothering anyone. The painfully shy cat, Chewy, who was her former victim, is sitting calmly less than a foot away from her on the bottom left. They had NEVER been that close.
I highly recommend the cat trees by ARMARKAT. You can look on their website, or look around on Amazon and eBay, where they are also sold. They are sturdy, well-designed and constructed and stylish.
We have many assorted perches, hammocks, pedestals and beds throughout the house, and the cats use all of them interchangeably. It also helps cats keep off your furniture, and gives them something more fun and satisfying to scratch on.
Jackson Galaxy also has a new book just out that should be a must-read about designing cat-friendly environments. I've met Jackson a few times and he is the real deal - he is exactly like how he is on TV; warm, friendly, funny and totally unpretentious. He has a fantastic website, blog and various books.