I feel my boys need more entertainment 
They have a large 70x240cm indoor cage with 2 houses, some tunnels and balls and soft, fleecy bags for hiding in. And hay, of course, hay.
They seem to enjoy the empty toilet rolls that DS3(6) insists on giving them and nibble away at them (and their wooden houses).
They are totally ignoring the wooden football themed
chew-toy that we 'had' to get 2 of at insistence of DS4...
So, what other 'toys' do your GPs have?
Hammocks? More tunnels?
Do you swap stuff around?
Inspire me - homemade or shop-bought, all ideas welcome.