How often do you play with them?

Cats are creatures of habit. They love routine. They thrive on it. Play with them at the same times every day, and soon they will come to know when those times are. At other times, they will play by themselves, with one another, or relax.
Pay close attention when you play with them, they will tell you what kind of Games they like to play. Cats invent new Games all the time. It's a lot of fun, playing with the cats. It's just as good for the human as it is for the cats, really!
Size of home doesn't really matter. What matters is that they get enough interactive stimulation, mental and physical, from you.
Do you have a cat tree? If there is no room for a cat tree, install shelves on the wall for them, to jump and climb and perch on. And/or set up book cases against a wall, in a stair step pattern. They need elevated space more than they need wide expanse of running room.
I have a tiny apartment. My furniture is arranged so the cats can fly around the room without ever touching the floor. Couch to chair to book case to desk to TV, and so on. In the bedroom I have the bookcases arranged in stair steps I mentioned above. They run up and down them all the time.
My kitten is 18 months old now. She has other cats to play with, always has. But she still requires a lot of attention from me. Before I leave the house in the morning I throw a few toys for her, as I am getting ready to leave, and she chases them down. I keep a box of them handy, then leave them scattered when I leave.
I get out her string on a stick and swing it around for her to leap and chase for a couple of minutes too. I put the string on a stick away before I leave the house (that kind of toy should never be left out).
When I get home at night I'm tired. Sometimes really really tired. But if I don't play with the kitten, she'll get into mischief. So I spend my first 30 to 45 minutes after I walk into the apartment playing with her and the other cats.
Later, after they and I have eaten, and I've washed up, had my computer time and done any chores, I read on the couch before I go to bed. I keep a box of toys next to the couch to throw. I toss them across the room and she chases them down. I toss them so they go up on things, and she leaps after them. I do this while I am reading. After a while she starts playing with one of the other cats or by herself with one of her favorite by-herself toys.
You can't remove behaviors that are natural and instinctive. You risk destroying their spirit. Cats are cats, it's just their nature to want to get into things, knock things down, jump on things. Give them the outlets they need to satisfy those natural behaviors, so they won't get into trouble.
The more you play with them, the more they will play by themselves. When you play with them, you help stimulate their imaginations, and then they are able to entertain themselves, when you aren't there, or are busy, or sleeping.
Speaking of sleeping, the more you play with them, the more they play by themselves, and that means,
they will sleep at night, when you do.
The more time and effort you put into them now, the nicer they will be, when they are all grown up. But, now matter how old they are, they are always going to want and need your attention, and interactive play, every day.

PS Travel and strange places can be very stressful and rough on cats. Some cats adapt immediately, but many don't. So don't expect too much from them, on the visit to your family. Hope it's fun.