I don't think having no pet would make me happy although, when Cleo is gone we won't rush into getting one as we're looking to do a long trip around Australia in our caravan, a year or so, and taking a cat wouldn't work so well. We'll see.
As a kid we had an aviary with budgies, finches and canaries in it...it was nice to hear them chirping happily and their colours were nice. I don't like to see them locked up now though.