Hi Mark! It's good to hear from you
Oz and Charlie are beautiful, and they look very happy with their new palace
It looks great!
Although they want to stay up top (which, you're right, is a natural instinct which helps them stay out of reach of some predators in the wild), you can move perches and some toys down a little, as well as have their food dishes down low so they're encouraged to go down and explore
With a little coaxing, they should settle into taking full advantage of their palace soon!