I faced the same issue myself before I moved into a house. At first I went with an electronic keyboard. The problem is, that an electronic keyboard doesn't reproduce the same control, sensitivity, touch and expression of a real piano.
I talked with the neighbors and was very careful about observing quiet hours. They turned out to be pretty cool about the whole situation and wound up being very encouraging.
So, I wound up selling the electronic keyboards and got a real piano. I'm much happier too. Morale of the story: if you want to play a piano, get a piano.
I have an electronic keyboard these days, but I consider it an entirely different instrument than a piano. I use it for things a piano doesn't do as well such as orchestration and composition.
One more thing: they now have some systems on accoustic pianos that allow you to play quietly. See PianoDisc., etc. I'm not up on how these work, but one of the techs on the forum can explain the details.