Here are Hobart (female) and Nemesis (male), my marble angels. They were bought in summer 1997, so they're about 8 years old, but as you can see, their age doesn't seem to bother them too much.
They're in a ~200 l (53 gal) with 13 bronze cories and 2 whiptails. So they do have company, but they have the top and middle layers of the tank to themselves.
Alas, they don't seem to know how to be parents. It seems they were bred by people who were more interested in how they look instead of how good they are at parenting.
That's one reason I get so annoyed when I see people suggest you raise angel (or any cichlid) fry away from their parents, since that eventually leads to bad parents. As I feel the natural behaviour of fish is just as (if not more) important than looks, I haven't even tried raising the fry, even though I'd love to see the little ones grow. However, it's been going better and better for Hobart and Nemesis each time, so I hope they'll get the hang of it one day. Maybe they're just slow learners. They only started spawning less than a couple of years ago for some reason, so they haven't had that much practise yet.