Rabbits or Cats are litter box trainable....and cats are so much more independent than dogs are. Of course, I am NOT advocating that you leave your cat or bunny alone all the time! They love companionship (at least most of them do), but they are more solitary than a dog is.

We have hamsters, which are "low maintenance" but need to be held daily to keep them tame. Guinea pigs require a little more attention though and you're already handling that one fine!

Let us know what you decide. I think if I were you, I would want to get a "pair" of something, to make sure they would keep each other company. What about another piggie??