Cat care tips:

Have a cat pan on each level of your home. IF they have access to your basement, make sure there is a place down there for them to use the loo.
Feed in two separate places, it makes them move around and get exercise and cuts down on fights.
Empty boxes are the second best cat toys with only the plastic ring off a milk jug being better. Trust me. I've bought the nice toys and had them ignored for boxes and milk jug rings/lids.
Cat nip does not always make them hyper. Some will get mellow off the stuff.