There are some crazy awesome setups out there.
This is my PetCo Rat Manor. It's home for my two male ratlings, Nibbles and Skittles.
It's two levels with two shelves, I read about wire flooring being bad, so I laid a hardboard base over all of the upper shelves and floor and topped it with self-stick floor tile. I dressed all the edges with duct tape to discourage chewing, hoping that the adhesive might have annoying after chewing effects like sticky teeth, heh.
I have two food dishes to make food a foraging experience of sorts. The long stem coconut cup is for lab block or other dry food (plus you can hide stuff in the no-man's land between the stem and the cage bars) and the bar-mounted feeder cup is nice for fruits, veggies or other surprise foods.
Those bendy bird perches are pretty cool, you can adjust the shapes once in a while to keep things from getting boring and change things around a bit.
The rats took to a far corner as the potty spot, despite my best efforts at trying to get them to use an area easier for me to access. They have been pushing the houses around lately, so this might be a chance to try to change the spot.
Looks like more hanging gear can be put in with m'rats, I'll start looking around for tubes and some hardware. I can probably fit a little more stuff in there while they are still smallish, sizewise.
Some rats might use an exercise wheel and some will just use it as a place to hide. I suppose they are cheap enough to try out, or even rotate it with the weekly litter/toy change.
I'm thinking that they are fairly comfortable in there now, when I take them out they'll try to head back to the cage, which is good, cause I don't want to play "hide and seek" and "catch the rat" all night. The free roam area is in another room, so if they do get loose, they have no clue where they are, but the area I have set aside for them is pretty easy to secure quickly, and fairly easy to clean up after any accidents.