Do they have their own furniture to climb up on? I found when I bought my cats their own furniture to scratch and play on... and "rewarded" them for using it (also apply a liberal amount of catnip to the "ok" areas), they tended to leave my stuff alone.
If they like being up high, perhaps you can look into buying or building a tall cat tree?
In my experiences, kittens tend to have more tendency to climb than when they grow older. I couldn't keep Voltron off anything when he was a kitten; now he's maybe 1 1/2 years old and he doesn't have that "wild" energy anymore so he's calmed down quite a bit.
Bookmarks