When I received my bunny for the first time, she was dropped off in medium sized cage along with a bag of timothy hay and pellets to get me started. I transferred her to a playpen that is around 33 inches by 65 inches with a height of 25 inches. My bunny is not a high jumper likely because of her arthritis so 25 inches is ample. However, you may have a hopping Houdini and need a higher pen, especially if you have a house that they can jump onto to help them clear the pen's height.
Initial set up:
Pen on top of disposable wee-wee pads. I found it best to tape them from underneath to keep them from sliding all over the place since I have hard flooring.
Plastic hay feeders: one on the outside of her litter box and another attached to the inside of her litter box.
Large black litter box with high sides and a lower entrance: filled with newspaper lining and paper based bedding. Mat underneath box to prevent it from moving since she loved to shove the box around. She is little but mighty.
Small light weight bowls for her pellets and food. She usually has a third bowl for her veggies but it isn't pictured below.
Small wood based tunnel with some chew toys and a grass mat.
Placed outside of her pen: strawberry house with a plush inside and foam based support placed on the outside of her pen for her to chillax in.
But as with any bunny they love to chew and in her case dig, so her pen would sometimes look like the following depending on her mood.
The culprit tried to look as innocent as possible.
Setup 2:
Pen on top of a 5 foot by 7 ft Ruggable. It is machine washable and I can easily sweep the hay off it, but it has very little padding, so I did need to add some extra small blankets in areas where she spent most of her time resting. My bun is an odd one because she does not like soft, thick surfaces. I once laid thick blanket through half her pen during winter and she was lying everywhere the blanket was not. I'm thinking it is because it may get too hot for her. She did this for a good 1-2 weeks until I gave in and removed it.
Ditched the two plastic feeders since it made more sense to have her hay all in one place and also because bunnies like to go to the bathroom while they are eating. Tried adding a large wood-based holder to same litter box so it would hold much more hay than the other feeder. As you'll see below, it did not work out well.
I changed out the lightweight bowls for ceramic bowls that are unflippable because you guessed it, she loves tipping and tossing items including her food bowls. Of course she did this while most of the pellets were still in her bowl! Otherwise, it wouldn't be as much fun.
Small wood tunnel remained with grass mat but had to get rid of the strawberry house because she was treating it like a litter box and only spent just enough time to do her business and leave.
Below is a transition between setup 2 and setup 3
This was the new feeder that replaced the plastic one but she figured out a different way to use it so it ultimately became a litter box within a litter box. Had to get rid of it too. And that little pillow on the left was hopped on once and never used again because of it's soft and thick texture.
Setup 3:
Decided to get one of those Etsy feeders with the litterbox tray holder and have used it ever since. I like it because it also has a lower entrance so it'll be easier for her to get in when she gets older. Right now, she is still spry as ever and chooses to jump over the higher sides most of the time. She is a digger so tried using the fine mesh tray (pictured below) to put over the paper litter since it was ending up all over her pen. But she quickly figured out how to flip it up and out of the box even when it was covered with hay. Yes, I came home to this mess one evening so no more tray.
I'll also switch on her lamp a few times a week to simulate some sun rays for her bone health since it's not safe for her to be outdoors especially with that rabbit virus going around. She does get her yearly vaccination against it though.
Changed to a much smaller veggie bowl pretty early on since she eventually got an upset stomach and one of the many vets I've gone to finally told me to cut down on the amount of veggies. Her stomach has been great ever since.
Ultimately decided on paper pellet litter due to its weight and absorbancy and it is much easier to clean if she decides to dig for the day.
(Pictured below) Her wood tunnel was upgraded to a little house that I made for her, and she has a blast playing with her mobile play station among other chew toys and her grass mat. It keeps her old bunny mind going.
Due to the hard flooring and the fact that she only has fur covering her feet with no pads like a cat or dog, I also added black workout puzzle matting throughout the main living area. She seems to enjoy it and gets around a lot easier.
Final additions: Throughout her almost 4 years with me, I've made it a point to change the out-of-the-playpen area for her every now and then. She has little houses with ramps, tunnels and places she can makes small jumps to and seems to enjoy it. She wouldn't touch the ramps until I folded little blankets along the ramp because it was too steep and slippery for her. Now she runs up and down with no issue. I also added a cot for her, and she seems to like to rest on that compared to all the small soft pillows and blankets I've bought in the past.
Final thoughts:
It'll be best if you are flexible to your pet's needs when deciding the best living space for them.
Determine their likes and dislikes to make the next best choice when changing their habitat.
Some bunnies like to toss things including their food bowls, so you'll probably want to get heavier bowls to prevent this.
If you get a thin carpet for your playpen, you may have to add additional padding or grass mats in places where they rest the most to protect your bunny's feet.
To minimize chewing on your furniture, make sure your bunnies have plenty of things to play with. They may also go through phases where they'll like one type of chew toy for while and prefer a completely different type later in life.
Hopefully this article will save you some time and money and ultimately help you optimize the living area within the first 1-2 attempts.
Make it a fun experience so if you are crafty, try to create some interesting habitat components for your bun like toys or hideaways.