My cage is almost identical to the Hamster Heaven - it's basically the same cage but with smaller bar spacing and without the contents, tubes and penthouse. The measurements are identical and it has the same big front door. So I started out with a blank cage basically. I did have one of the Hamster Heaven platforms in at one point (the one with the pod house) but took it out and set it up from scratch.
This was the first set up
I had his Karlie Wonderland wheel back left with the substrate sloping up away from it towards the front of the cage where it's deeper. Before I had the vine branch front left the floorspace was open here and Charlie liked to leap out of his wheel while it was spinning and lie on that bit of substrate. But he didn't like the bare open corner and was much happier when I put the vine branch in there. It also provides access to the far side of his rat sputnik. The house is a guinea pig house which doubled up as a shelf and the bendy bridge was over the door to a) provide a ramp up to the top of the house and b) cover the door to the house which was really large with it being a guinea pig house. But it also made the house much darker inside and he went straight in there and built a nest.
The cardboard tube is the medium 10cm boredom breaker tube. I put it there because Charlie kept jumping out of that side of the sputnik and it was a bit close to the bendy bridge. He loved that as it was a roof run between his house roof and the sputnik. He likes the big sputnik now I've lined it with a cut out circle of hemp mat to make it cosier.
Back right, the purple thing is a small lava ledge - he likes sitting under there and it also is something to climb on from the far side of his small sputnik.
I like the big sputnik where it is near the front because the front hole is near the big front door, just offset to the left of it a bit, and he likes to climb out of the cage from there, and be put back in near it so he can climb into it.
Here's Charlie sitting in the big sputnik (waiting to come out!)
This is his current set up. It's virtually the same, but the house is slightly bigger and the bendy bridge is smaller. The house has a lift off roof which I really like as it easy to check on him, his nest and his hoard, while leaving the rest of the house part buried in substrate. His wheel has changed to, to the Wobust wheel, which is huge and a bit too big for the cage really, but his Wonderland wheel broke and it took so long for another one to get here (I had two faulty ones sent) that I got the Wobust wheel quickly and he liked it so much I left it in. Charlie is a particularly large Syrian so you'd do better with a 27cm wodent wheel or Karlie wheel, but the wodent wheels fit very well in these cages as you can hang them from the top bars. With the 27cm one you'd still have a fair bit of space under it for substrate so wouldn't lose as much floor space as you would with the Karlie one.
He moved his wee corner into the big house, so it also has his potty inside, which works well as the rest of the cage stays clean.
So I'd recommend a large-ish house with a flat roof that lifts off, and doubles up as a shelf/platform, plus a wodent wheel and a rat sized sputnik.
Rodipet do some really great houses for hamsters, with lift off roofs. It's fairly easy to order from them - they take paypal - you just need google translate to translate the ordering page.
I think the third one down on this page is good (3 compartments)
https://www.rodipet.de/shop/haeuser/rodipet-granit/
This one is also good - it's about the same size as the first guinea pig house I had
https://www.rodipet.de/shop/haeuser/...-duoporta.html
They also do very good labyrinth houses, but they would take up a huge amount of room in my cage/the hamster heaven, so I got the Ferplast Sin Rabbit house instead, which is completely open inside and smaller than the labyrinth houses.
They now have a slightly smaller labyrinth house though which is a similar size to my house - lots of compartments for hoards, a nest and a potty.
https://www.rodipet.de/shop/haeuser/...x28cm-6cm.html
The Trixie Leif Labyrinth house is popular too, and is ok unless you have a large Syrian. For a Syrian it's probably best to knock out the centre divider so it's not so cramped.
http://www.amazon.co.uk/Trixie-6201-...abyrinth+house
The advantages of the labyrinth houses are they are already dark inside so you don't need a tunnel over the door. Plus hamsters really like them
I have also had one of these in the cage at various times - Charlie didn't use it much as a hide, but he did use it as a step up to the far end of his house and out of the far side of his sputnik and he liked sitting on top and nibbling the roof.
http://www.amazon.co.uk/Rosewood-Nat...ottage+hamster