Hello Josh ^.^
So I debated getting a Critter Nation cage for years. Then, once I did a TON of research and decided that it really was the best cage to buy(still believe that now that I own one!) I also struggled with the idea of buying a single or double unit.
For me personally, what it came down to was that buying a double was cheaper in the long run by a good amount of money than buying a single and later deciding to purchase an add on unit to make a double.
Also, since the single unit is lower to the ground, having the double is nice because I put their food/water/litter box and their main sleeping places and toys on the top section so they spend most of their time up there. Not only is it easier to see them and interact with them but because they spend 75+% of their time up there, I don't have the clean the bottom very often at all.
As far as too much space goes, in my opinion they can never have too much space. I keep the bottom of the cage pretty bare, there is only a corner litter box and a big hammock, and they love to use that space to just run around and play. Not to mention, it also leaves you with the ability to adopt more rats in the future if you want to, and still give them all a lot of room and personal space.
Obviously the choice is yours and I'm sure you and your rats will be happy with whatever you decide, but I highly recommend the Double Critter Nation cage or even just a single. After owning all kinds of different cages, I'll never use anything else as my main setup.
So I debated getting a Critter Nation cage for years. Then, once I did a TON of research and decided that it really was the best cage to buy(still believe that now that I own one!) I also struggled with the idea of buying a single or double unit.
For me personally, what it came down to was that buying a double was cheaper in the long run by a good amount of money than buying a single and later deciding to purchase an add on unit to make a double.
Also, since the single unit is lower to the ground, having the double is nice because I put their food/water/litter box and their main sleeping places and toys on the top section so they spend most of their time up there. Not only is it easier to see them and interact with them but because they spend 75+% of their time up there, I don't have the clean the bottom very often at all.
As far as too much space goes, in my opinion they can never have too much space. I keep the bottom of the cage pretty bare, there is only a corner litter box and a big hammock, and they love to use that space to just run around and play. Not to mention, it also leaves you with the ability to adopt more rats in the future if you want to, and still give them all a lot of room and personal space.
Obviously the choice is yours and I'm sure you and your rats will be happy with whatever you decide, but I highly recommend the Double Critter Nation cage or even just a single. After owning all kinds of different cages, I'll never use anything else as my main setup.