I love the look of 2 story houses but since I was diagnosed with cancer 3 years ago my mobility has suffered greatly. I have melanoma that first made itself known on the bottom of my left foot. My left leg from the knee down is a mess. I'm very grateful we live in a 1 story house. If you plan to retire in a house I recommend a 1 story house. That way if you do end up with mobility issues like so many people do, you will still be able to use your whole house.
Rodney