This is my current setup. I'm still experimenting though. My hamster seems content with the cage size (never chewed on bars or demonstrated any desire to escape at all). However, my hamster is also very shy and timid, so I would like to find a layout that would allow him to feel more at ease. He is quite peculiar though
He likes his big wooden house that came with the cage. He adores his wheel - he runs in it, snacks there and takes naps there in between running. He also likes to dig around and roll in his corner sand tray. But he doesn't demonstrate any interest in anything else I put in his cage (any chews, hideaways, tunnels, sputniks (both hamster and rat-sized), hanging toys, DIY puzzle toys). I keep on trying though