i am of the 'a pet makes a house a home' mind set Im afraid.
I am with you on not getting a pet you are allergic to, or that you would end up having to care for.
However the appearance of your house? Sorry.. pardon? Its not just your house is it, it's your families home. Surely the happiness of those who live there is more important than appearance?
I have dogs, which are certainly not for everyone.
I also have dart frogs which are great - they live in a biologically appropriate viv, live plants, heating built in, mister system to keep it humid..
Yes, it was expensive to set up - but now, we just feed daily, make sure the water reservoirs are topped up, and prune the plants once every few weeks. We get to enjoy silly froggy antics (they are very comical once they know you and will come out and see you) and the tank to my mind looks pretty attractive, basically being a glass box with a living jungle inside.
I do think kids get a lot from looking after animals, and certainly better for them to learn this now than as young adults in their own first homes, where mistakes are typically made and its the animal that suffers.